As I came to terms with the realities of being in lockdown I needed to come up with strategies to help my clients keep moving towards their goals. I decided to take the time at home as an opportunity to shed some body fat.

Obviously sensible dietary choices were going to be essential to this, but with my usual physical activity drastically reduced (that’s what happens when you trade 8 hours a day on the gym floor for sitting in front of your laptop), I needed to be intelligent about my training. One of the key tools I used for that is high-frequency weighted cardio.

To be able to take a high-frequency approach to any training method you need to be able to recover quickly. When it comes to high-frequency training, high levels of muscle damage, and being sore for days are public enemy number one!

There is one often neglected training method that causes almost zero muscle damage but provides a powerful training stimulus. And that is the method I will use to lean down during lockdown. So, here’s how I progressed on my lockdown plan.

Concentric-Only Training

There are two main phases of muscle contraction during resistance training:

1. Concentric Muscle Training
2. Eccentric Muscle Training

The concentric phase is when a muscle shortens under tension. You can think of this as the lifting phase. The eccentric is when the muscle lengthens under tension. This is the lowering phase.

The eccentric phase is where most of the muscle damage occurs. Eliminating the eccentric phases means you can reduce the stress, muscle damage, and breakdown that occurs with traditional training.

I wouldn’t suggest excluding all eccentric training form your program indefinitely as the eccentric portion of the lift does carry many benefits and is a key piece of the size and strength puzzle. However, tactically removing the eccentric phase from certain elements of your training can have powerful benefits.

Concentric-only training creates the potential for:

1. Higher training frequency
2. More volume

Those are both very useful when it comes to fat loss. Even better, a 2017 study (Stock et al., 2017) showed that concentric-only strength training (involving minimal muscle damage) produced hypertrophy in just 3 – 4 weeks. So, concentric training can help you get lean and gain (or least preserve) muscle mass.

Research shows that concentric-only training produces much higher metabolic demands than eccentric training (Kraemer et al., 2001). Significantly greater VO2 and lactic acid levels are reached with concentric-only training. This increased metabolic cost equates to more calories burned.

Improved Recovery with Concentric-Only Training

Concentric-only training is very popular in injury rehab programs. In the early stages of rehab, many therapists use high-frequency concentric-only training as the first step in strengthening muscles.

Improved recovery from injury is one benefit of concentric only training. Enhanced recovery between sessions is also a big plus of concentric only work.

Stimulating blood flow to the working muscles improves the recovery time from one heavy session to the next. This is why concentric only training is such a great addition to your regular workouts.

Bonus Training Not Overtraining

Concentric-only training means you can do extra or bonus training with a much lower risk of overtraining. Concentric only work allows you to get a training stimulus without the mechanical or neurological fatigue that regular training causes. Consequently, you can do more training with minimal risk of it interfering with your usual lifting sessions.

The more you can train without exceeding your capacity to recover the better your results. The fact that concentric training gives you the ability to increase your workload without exceeding your recovery capacity is a huge bonus when it comes to winning the body fat battle!

Powerlifters, Concentric Lifts, and Conditioning

Westside Barbell popularized concentric-only training with the use of sleds for conditioning work. Pushing and pulling a sled is an incredibly effective fat-burning workout. I’ve used it in the programs of countless clients to great effect. It’s one of the best ways to maximize fat loss while minimizing muscle loss.

Unlike traditional cardio, sled work involves relatively high levels of resistance. This resistance signals the body to keep hold of muscle. As a result, you don’t waste away to looking like a marathon runner when performing weighted energy system work.

Concentric-Only Training at Home

Sadly, I don’t have a sled or enough outdoor space to use one. Living in central London means space is at a real premium. What I do have is 6 flights of stairs in my apartment block and these are what I’m using to get the same benefits of sled work.

Here is how:

• I load my backpack up with books and dumbbells
• I walk up the six flights of stairs
• I get in the lift and return to the ground floor
• I repeat for 5-10 sets

Walking upstairs is a predominantly a concentric activity. By loading my backpack up with textbooks and dumbbells I am able to add 50 lbs of external load. Walking up the stairs is like doing a hundred weighted step-ups.

I get in the lift to go back down because I’m lazy. Obviously, I’m joking, there is actually a method to my madness/laziness. Walking downstairs with 50 lbs of extra weight involves lots of eccentric work and causes plenty of muscle damage.

Walking up and down stairs would mean that I would be sore and recovery would take longer. As a result, I wouldn’t be able to do this on a daily basis. Since I’m looking to use this method as my daily cardio taking the lift down is the smart choice.

So, if you have a backpack, something heavy to put in it, and a staircase, you can get shredded while self-isolating.

Now, it looks like there is a sense of normality returning, although I think some people may still choose to workout at home until they feel comfortable going into a gym. Connect with me on my Tom MacCormick Instagram account and message me if you need some help.

The post High-Frequency Fat Loss – What I Learned in Lockdown appeared first on Breaking Muscle.

Photo By Bev Childress

Traditional programs to combat weight gain focus on nutritional (calories in) and exercise (calories out) considerations. Many health-related professionals agree that dietary guidelines likely best serve to promote short-term reductions in body fat, with the impact of exercise being helpful, but perhaps not overwhelmingly. Even so, from the perspective of physical movement, questions can be raised as to which is more meaningful:

1. The increased caloric costs associated with daily exercise and activity, or
2. An increased ability to oxidize fat.

In fact, the caloric costs of any given format of exercise are typically not great, being at best low to moderate. However, in terms of optimizing the prevention of body fat accumulation, it is suggested that exercise program design should focus on brief, intermittent phases of intense work, followed by more prolonged periods of active recovery.

The Deceiving Apparent Simplicity of Fat Loss

A staggering 2 out of 3 adults are overweight or obese. Equally worrying is the lack of an apparent strategy to ward off such a trend. One basic perspective has been the perhaps overly-simplistic relationship between calories in and calories out. Based on that premise, there are three straightforward approaches to weight loss:

• Curtailing caloric intake (i.e., diet)
• Promoting caloric expenditure (i.e., exercise)
• Some combination thereof

A focus on caloric intake is of course crucial to weight loss, but is negligent regarding the bioavailability of the calories within food, especially processed food. Indeed, the caloric content of what we ingest does not necessarily reflect the amount of energy that is actually obtainable by the human body. Processed food makes calories more readily available as compared to un-processed food, leading to the potential for increased energy availability with subsequent body fat gain.^{1, 2} In fact, counting calories is often portrayed as a losing endeavor.

The caloric expenditure side of things is similarly suspect. We know that exercise can affect body composition, and a growing body of research suggests that brief, higher intensity intermittent exercise may be even more effective at promoting reductions in body fat than its lower intensity, steady-state counterpart.^3,4 Yet exactly how that works remains to be seen. Is the exercise-related loss of body fat more dependent on increases in caloric expenditure (both during and after exercise),⁵ or is it because of a greater reliance on fat as a fuel?⁶

The Complications of Calories Out

Exercise invokes an increase in metabolic rate regardless of the design: steady-state or intermittent, low, moderate, or high intensity. From the perspective of caloric cost, steady-state aerobic exercise (e.g., walking, jogging, bicycling) takes time, while brief bouts of intermittent exercise (e.g., resistance training) demand exertion.

Truth be told, dependent on how much time you have or your willingness to apply effort, the calories just don’t add up in terms of making an overwhelming contribution towards the immediate removal of body fat. To be sure, metabolic increases are the result of any kind of physical movement, yet at 4000cal per pound of fat, you need to complete quite a lot of exercise to lose a significant amount of weight.

In the table below, taken from my book, ten bouts of each proposed exercise routine are required to lose one pound of fat. The costs of walking, jogging and cycling come from steady-state measurements; all other examples are estimated in a cost per task format.

Another popular belief is the resulting caloric after-effect that regular workouts provide. Exercise physiologists call this excess post-exercise oxygen consumption (EPOC); fitness professionals refer to this period as the “afterburn.” Regardless of terminology, many of us consider exercise as an unequivocal promoter of an increased metabolic rate, yet recent investigation suggests far worse.

A study of what can only be considered an above-average active-population—a hunter-gatherer tribe—revealed that daily caloric costs were comparable to those of a “standard,” similar-sized, sedentary apartment dweller.⁷ Intuitively, it would appear that the physically demanding lifestyle of a society that eats only what it catches or forages, would result in a daily energy expenditure greater than that of someone who, with a smart-phone, can voice-command a pizza delivery at any time of the day. The author of the investigation suggests:

“…the body makes room for the cost of additional activity by reducing the calories spent on the many unseen tasks that take up most of our daily energy budget; the housekeeping work that our cells and organs do to keep us alive. Saving energy on these processes could make room in our daily energy budget, allowing us to spend more on physical activity…”⁸

What Are We Measuring?

How could the exercise science and fitness communities be so wrong? Many of us have been trained to champion the idea that regular exercise, at the very least, provides some kind of addition to overall daily caloric expenditures, not a subtraction. The answer may not lie solely with absolute caloric costs per se, but also in terms of relative considerations, as the type of substrate or fuel from where those calories come from.

The calorie is a historical unit, created when the direct measurement of heat served as the gold standard in the quantification of life’s energy exchanges. Due to time and expense, heat measurements—calorimetry—have been replaced with oxygen uptake measurements, the latter serving to estimate heat production.

In terms of the measured volume of oxygen (O₂) consumed, glucose oxidation results in a greater caloric cost (~5.0cal per liter of O₂) as compared to fat oxidation (at 4.7cal per liter of O₂), a difference of about 7%. But let’s look at the inverse. When caloric expenditure is estimated by units of oxygen consumed, the following conversions are noted, per calorie:

• Glucose oxidation = 0.20 liters of O₂
• Fat oxidation = 0.21 liters of O₂

From that perspective, the oxidation of fat compels a greater volume (~5%) of oxygen consumed per calorie; that is, an equivalent need or demand for energy results in a greater amount of oxygen consumed when fat is “burned” as a fuel, compared to glucose.⁹

The daily energy needs of the hunter-gatherers mentioned earlier utilized a methodology where the estimate of daily caloric costs came from the calculated amount of carbon dioxide produced, not the volume of oxygen consumed. From the perspective of energy demand, the oxidation of fat results in proportionately less carbon dioxide production, and a greater oxygen uptake than does the oxidation of glucose.¹⁰ This means that a similar rate of carbon dioxide production between sedentary and active populations may falsely indicate a lower than actual metabolic rate for active people.

Can We Just Burn Fat?

If caloric costs don’t provide a straightforward explanation for exercise-induced weight loss, perhaps the answer lies more with the ability to oxidize fat.

While the association between a decreased ability to oxidize fat with subsequent weight gain is weak, it is also statistically significant.^{11, 12} Increases in fat oxidation have been found after exercise.^{6, 13, 14, 15} Yet evidence also is available to suggest that the rate of fat oxidation between sedentary and active populations is not much different.¹⁶ Factor in the frustrating variability associated with the measurement of substrate oxidation during non-steady-state exercise and activity, as well as the ever-present influence that diet also provokes,¹⁷ and a conclusive take on an increased ability to oxidize fat cannot be made.

One bit of solid evidence regarding substrate utilization and working skeletal muscle is that the higher the intensity of exercise, the greater the reliance on glucose (glycogen) as a fuel. This has led to the conclusion that exercise designed to lose body fat should be of low to moderate intensity and longer duration: steady-state cardiovascular exercise (e.g. walking, jogging, bicycling). Times have changed.

We Need More Accurate Research

The focus of exercise and its associated energy costs within most exercise science labs has been on low to moderate intensity, steady-state exercise. Treadmills and bicycle ergometers serve as traditional equipment, and standard costs are reported in a per-minute format (i.e., liters O₂ or calories per minute. As a direct yet baseless result, equivalent descriptions are also used for higher intensity, non-steady-state (intermittent) exercise.

Clearly, low to moderate intensity steady-state exercise and higher intensity non-steady-state exercise are not the same, yet many exercise scientists continue to estimate the caloric costs of both using standard per-minute measurements. Likewise, it needs to be kept firmly in mind that the published energy cost estimates of steady-state exercise do not include recovery.¹⁸ For intermittent non-steady-state exercise, this practice has been questioned, as it may misrepresent both the absolute and relative aspects of the caloric cost and fat-burning benefits of intermittent exercise, respectively.^{19, 20}

While not yet a mainstream methodology, energy requirements also have been estimated in the context of a cost per task, where an amount of work is completed along with the total energy costs of that task. A total energy cost estimate consists of three specific measures:

• Exercise oxygen uptake
• Anaerobic costs (based on blood lactate levels)
• Recovery oxygen uptake (measured between bouts or sets, as well as after exercise is completed)

How Building Muscle Burns Fat

Resistance training, where work is performed as the number of repetitions completed in a per-set format, serves as a wonderful example of high-load, non-steady-state, intermittent exercise. Under these conditions, it has been reported that as the number of sets increases within a given workout, the amount of recovery oxygen consumed between sets increases in apparent proportion to the decrease in anaerobic costs.²¹ Because there is little to no intensity associated with recovery, conditions for fat oxidation appear optimized.

Within 3 sets of a specific resistance exercise, aerobic recovery costs grow larger, while the estimated anaerobic exercise-related costs decrease (based on blood lactate levels), setting the stage for moments of increased fat oxidation.

Higher intensity exercise most certainly demands a greater cost to physical movement. A decreasing blood lactate cost-to-work ratio among sets of repeated high-intensity resistance exercise along with an increasing recovery oxygen uptake indicates an increased use of the high-energy phosphate stores of ATP and phosphocreatine (PC) within muscle during the repeated act of weight lifting. Afterwards, in the recovery between sets, a good deal of oxygen is consumed to replenish those high-energy phosphates stores, and fat may be the preferred substrate that fuels that energy exchange.

The take home message is that an intense intermittent exercise workout, or rather, the presence of multiple recovery periods within that workout, may serve to better oxidize fat as compared to a single lengthy bout of steady-state exercise followed by a single recovery period.²² With a focus on recovery, a case can be made that brief bouts of heavy work followed by a somewhat lengthy recovery period might optimize the use of fat as fuel.

When examining resistance training work between separate workouts performed on different days of high and low loads, an analysis of the work to total energy cost ratio revealed that efficiency actually improves as more repetitions are completed.^{6, 22} That is, lower loads with a high number of repetitions are more efficient, as compared to higher loads with few repetitions—even as more work is completed with the former, at a greater exercise-related cost.

When comparing energy cost efficiency among different resistance training workloads, lifting a heavier load with fewer repetitions is less efficient, as compared to lifting a lighter load for many repetitions. In fact, efficiency rises to a maximum as more work is completed. Data from our lab indicate that as aerobic and anaerobic exercise costs rise proportionately with resistance training work, recovery costs do not—EPOC or afterburn costs are somewhat similar among high-load and low-load workouts involving dissimilar amounts of work.^{22, 23}

However, as work increases with muscular endurance type resistance training, the amount of recovery-related oxygen consumption (i.e., recovery cost) appears similar for high-load, low repetition, strength training where less work is completed.^{23, 24}

To summarize, aerobic and anaerobic exercise energy costs rise linearly with increasing work, but recovery energy costs do not, being somewhat similar for high-loads with less overall work and low-loads where a much greater amount of work is completed.

Go Hard and Heavy, and Stay on Your Feet

Regular physical movement of any kind necessitates an increase in metabolic rate, if only temporarily. Coupled with caloric restriction, this almost certainly helps to reduce body fat. With the knowledge that most forms of exercise offer only a low to moderate overall caloric cost, exercise design should focus on what a person actually enjoys doing.

In terms of a more meaningful impact on longer-term, gradual body fat loss, exercise program design is suggested to consist of intermittent, brief, intense, high-load periods of inefficient work, each married to an extended recovery period. Recovery periods should, in turn, be active, involving lower-intensity, steady-state, large muscle group activities like walking, as opposed to passive (seated) rest, where higher rates of fat oxidation may be best achieved. A small but significant ability to oxidize fat day-to-day may better serve in the prophylactic prevention of long-term body fat accumulation.

References:

1. Roberts, Susan B., and Sai Krupa Das. “The Messy Truth about Weight Loss.” Scientific American 316, no. 6 (June 16, 2017): 36-41. doi:10.1038/scientificamerican0617-36.

2. Juul, Filippa, and Erik Hemmingsson. “Trends in consumption of ultra-processed foods and obesity in Sweden between 1960 and 2010.” Public Health Nutrition 18, no. 17 (2015): 3096-3107.

3. Boutcher, Stephen H. “High-intensity intermittent exercise and fat loss.” Journal of Obesity 2011 (2010).

4. Hunter, G. R., R. L. Weinsier, M. M. Bamman, and D. E. Larson. “A role for high intensity exercise on energy balance and weight control.” International Journal of Obesity 22, no. 6 (1998): 489.

5. Paoli, Antonio, Tatiana Moro, Giuseppe Marcolin, Marco Neri, Antonino Bianco, Antonio Palma, and Keith Grimaldi. “High-Intensity Interval Resistance Training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals.” Journal of Translational Medicine 10, no. 1 (2012): 237.

6. Bahr, Roald, Per Hansson, and Ole M. Sejersted. “Triglyceride/fatty acid cycling is increased after exercise.” Metabolism 39, no. 9 (1990): 993-999.

7. Pontzer, Herman. “The Exercise Paradox.” Scientific American 316, no. 2 (February 17, 2017): 26-31. doi:10.1038/scientificamerican0217-26.

8. Pontzer, Herman. “The Exercise Paradox.” Scientific American 316, no. 2 (February 17, 2017): 30. doi:10.1038/scientificamerican0217-26.

9. Scott, Christopher B. “Combustion, respiration and intermittent exercise: a theoretical perspective on oxygen uptake and energy expenditure.” Biology 3, no. 2 (2014): 255-263.

10. Scott, Christopher B. “Contribution of anaerobic energy expenditure to whole body thermogenesis.” Nutrition & Metabolism 2, no. 1 (2005): 14.

11. Zurlo, Francesco, Stephen Lillioja, A. Esposito-Del Puente, B. L. Nyomba, Itamar Raz, M. F. Saad, B. A. Swinburn, William C. Knowler, Clifton Bogardus, and Eric Ravussin. “Low ratio of fat to carbohydrate oxidation as predictor of weight gain: study of 24-h RQ.” American Journal of Physiology-Endocrinology and Metabolism 259, no. 5 (1990): E650-E657.

12. Seidell, J. C., D. C. Muller, J. D. Sorkin, and R. Andres. “Fasting respiratory exchange ratio and resting metabolic rate as predictors of weight gain: the Baltimore Longitudinal Study on Aging.” International Journal of Obesity and Related Metabolic Disorders 16, no. 9 (1992): 667-674.

13. Kuo, Calvin C., Jill A. Fattor, Gregory C. Henderson, and George A. Brooks. “Lipid oxidation in fit young adults during postexercise recovery.” Journal of Applied Physiology 99, no. 1 (2005): 349-356.

14. Henderson, Gregory C., Jill A. Fattor, Michael A. Horning, Nastaran Faghihnia, Matthew L. Johnson, Tamara L. Mau, Mona Luke-Zeitoun, and George A. Brooks. “Lipolysis and fatty acid metabolism in men and women during the postexercise recovery period.” The Journal of Physiology 584, no. 3 (2007): 963-981.

15. Bielinski, R., Y. Schutz, and E. Jequier. “Energy metabolism during the postexercise recovery in man.” The American Journal of Clinical Nutrition 42, no. 1 (1985): 69-82.

16. Melanson, Edward L., Wendolyn S. Gozansky, Daniel W. Barry, Paul S. MacLean, Gary K. Grunwald, and James O. Hill. “When energy balance is maintained, exercise does not induce negative fat balance in lean sedentary, obese sedentary, or lean endurance-trained individuals.” Journal of Applied Physiology 107, no. 6 (2009): 1847-1856.

17. Jeukendrup, A. E., and G. A. Wallis. “Measurement of substrate oxidation during exercise by means of gas exchange measurements.” International Journal of Sports Medicine 26, no. S 1 (2005): S28-S37.

18. Ainsworth, Barbara E., William L. Haskell, Melicia C. Whitt, Melinda L. Irwin, Ann M. Swartz, Scott J. Strath, William L. O Brien et al. “Compendium of physical activities: an update of activity codes and MET intensities.” Medicine and Science in Sports and Exercise 32, no. 9; SUPP/1 (2000): S498-S504.

19. Scott, Christopher B. “Intermittent resistance exercise: evolution from the steady state.” Central European Journal of Sport Sciences and Medicine 2, no. 6 (2014): 85-91.

20. Scott, Christopher B., and Victor M. Reis. “Steady state models provide an invalid estimate of intermittent resistance-exercise energy costs.” European Journal of Human Movement 33 (2014): 70-78.

21. Scott, Christopher B. “The effect of time-under-tension and weight lifting cadence on aerobic, anaerobic, and recovery energy expenditures: 3 submaximal sets.” Applied Physiology, Nutrition, and Metabolism 37, no. 2 (2012): 252-256.

22. Scott, Christopher B. “Oxygen costs peak after resistance exercise sets: a rationale for the importance of recovery over exercise.” JEPonline. 2012. 15:1-8.

23. Scott, Christopher B., Leary, M.P.; TenBraak, A.J. “Energy expenditure characteristics of weight lifting: 2 sets to fatigue.” Applied Physiology, Nutrition, and Metabolism. 2011. 36:115-120.

24. Scott, Christopher B., Brian H. Leighton, Kelly J. Ahearn, and James J. McManus. “Aerobic, anaerobic, and excess postexercise oxygen consumption energy expenditure of muscular endurance and strength: 1-set of bench press to muscular fatigue.” The Journal of Strength & Conditioning Research 25, no. 4 (2011): 903-908.

The post The Science of Weight Loss Loves Hard and Heavy appeared first on Breaking Muscle.

The Hypothesis

One hypothesis is that people with more fat also have a greater ability to burn fat. For example, if one woman had ten pounds of lean body weight and weighed 125lbs on the scale (twenty percent body fat) and another woman had the same lean body weight but weighed 135lbs (26% body fat), it is believed that the second woman will have a greater ability to burn fat.

There are a few reasons to think this might be true. First of all, it seems that macronutrient availability influences energy expenditure. This seems to be true regardless of how those substrates are available in the body. For example, consuming more of a particular macronutrient in your diet can increase your body’s willingness to expend energy from that nutrient.

Secondly, people with greater body fat levels have higher resting levels of energy expenditure. All of this points to the fact that when more energy sources are available, more energy gets spent.

Study Design

To test this hypothesis, fourteen women were tested for their body fat levels. Their fitness was tested via VO2 max, and their substrate utilization for both fat and carbohydrate was examined. Having the values for lean body mass, the researchers expanded the results by determining the substrate utilization rates relative to lean body mass.

Each of the women had similar amounts of lean body mass and similar macronutrient consumption in grams per pound of bodyweight. Both of these factors, if majorly different, could have influenced the results, so they were factored out.

Results

The researchers found that peak fat utilization occurred at around 55-60% of the women’s VO2 max. For most people, that pace would correspond to a heart rate averaging between 130 and 140 beats per minute, depending on age and weight.

As for body fat levels and fat burning, there was no significant correlation, but this is worth some discussion. In statistics, “significant” would mean that higher rates of fat burning could reliably be explained by some feature of the women, such as greater levels of body fat. However, just because that factor wasn’t found, doesn’t mean it doesn’t exist.

In statistics, a non-significant trend can still give you information, although that information might not be so reliable. When you look at the actual numbers here, there does seem to be a trend. The women with greater body fat burned on average about 100mg more fat per minute, which is about 25% more. It was also 2mg per kilogram of lean bodyweight more per minute for the higher fat group.

This trend seemed to hold across the studied variables. Combine this trend with the fact that none of the women were actually obese and the range in body fat levels was fairly small (from 18.6%-30%), and you wonder if a larger study might not have given stronger evidence.

To add fuel to the fire, the women were statistically considered as two groups, rather than individuals, and several of the women had body fat levels close to the cutoff point. For example, there was a woman in the lower fat group with 24.5% body fat where the cutoff was 24.9%. So, despite the statistically-correct conclusion, an analysis of the evidence shows a strong possibility that having more fat does indeed mean a greater ability to burn fat.

References:

1. Ashley Blaize, et. al., “Body fat has no effect on the maximal fat oxidation rate in young normal and overweight women,” Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000512

Photo courtesy of Shutterstock.

The post Does Having More Fat Help You Burn More Fat? appeared first on Breaking Muscle.

1. Fat Gain Signals Inflammatory Response

Adipose tissue is composed of white fat cells, which contain a large lipid droplet surrounded by cytoplasm with the nucleus on the periphery. When excessive fat is gained, these fat cells increase to four times their original size before dividing into new cells. Fat gain also alters the normal secretion of certain molecules throughout the body. While the exact mechanism is unclear, studies suggest that excessive adipose tissue can initiate an acute inflammatory response.⁶ Bone-marrow derived immune cells respond by infiltrating adipose tissue, and releasing certain molecules that can induce changes in fat cell activity and lead to chronic inflammation.⁶ This immune and fat cell activity cause downstream effects that can significantly affect your health when excessive adipose tissue exists in your body. Some of these effects are explained in further detail below.

2. Fat Cells Release Inflammatory Factors

Tumor Necrosis Factor α (TNF-α) is an inflammatory molecule released from adipose tissue. Overweight and obese individuals secrete TNF-α in greater amounts, contributing to insulin resistance.³ TNF- α down regulates GLUT-4, which is responsible for transporting glucose into skeletal muscle, resulting in reduced insulin function. TNF- α also reduces the activity of the insulin receptor, diminishing insulin’s metabolic effects and potentially leading to muscle insulin resistance.⁵

Interleukin-6 is another molecule released in greater amounts from excessive adipose tissue. Like TNF-α, IL-6 also down regulates GLUT-4, further reducing insulin function and contributing to insulin resistance. Increased IL-6 concentrations also induce the liver to release excess amounts of C-reactive protein (CRP) and fibrinogen in the blood, which are two of the major risk factors for cardiovascular disease and type 2 diabetes.⁶ IL-6 also increases the concentration and activity of blood platelets, which increases the risk for blood clots.² The activity of cells that line the blood vessels, such as endothelial cells and smooth muscle cells, is also affected by high IL-6 levels, contributing to vascular wall inflammation and damage.⁴

3. Fat Cells Cause Plaque Formation

Fat stores also affect your health by reducing the fat cell’s secretion of the anti-atherogenic, anti-inflammatory protein, adiponectin. This protein’s main function is to inhibit the buildup of adhesion molecules along blood vessel walls that lead to plaque formation. Adiponectin concentrations decrease as adipose tissue accumulates, placing you at greater risk for plaque formation, cardiovascular disease, and insulin resistance.³ Researchers believe TNF-α may be one of the contributing factors to the decrease in adiponectin concentrations.⁶

4. Fat Cells Can Become “Sick”

To further illustrate the dangers of accumulating excessive fat stores, a study by Bodenet al. (2008) in the Diabetes journal suggests fat cells from obese individuals are “sick,” due to significantly higher levels of stress to the cell. The authors explain that a constant influx of excess calories into fat cells can induce stress to the endoplasmic reticulum (ER), which is responsible for synthesizing lipids for storage. This stress triggers ER stress sensors, which activate various pathways in the body to alleviate stress. Researchers believe that this ER stress may be a contributor to the inflammation and insulin resistance associated with diabetes. 

In conclusion, adipose tissue does much more than only serve as an energy source. Fat cells are very active, able to communicate with immune cells and initiate an inflammatory response with excess calorie storage. Both fat and immune cells secrete various inflammatory factors that negatively influence normal and healthy functions of the body. As these responses become chronic with significant fat gain, you are at greater risk for chronic inflammation, cardiovascular disease, insulin resistance, and diabetes. Therefore, no matter how active you are, it is important to keep your body fat percentage at a reasonable level in order to maintain long-term health.

References:

1. Boden, G. et al., Increase in Endoplasmic Reticulum Stress-Related Proteins and Genes in Adipose Tissue of Obese, Insulin-Resistant Individuals. Diabetes, 2008. 57: p. 2438-2444.

2. Burstein, S.A. et al., Cytokine-induced alteration of platelet and hemostatic function. Stem Cells, 1996. 14: p. 154-162.

3. Diamond, A.S. et al,The Endocrine Function of Adipose Tissue. GGH, 2002. 18(2): p. 17-23.

4. Wassmann, S. et al., Interleukin-6 induces oxidative stress and endothelial dysfunction by overexpression of the angiotensin II type 1 receptor.Circ Res, 2004. 94: p. 534-541.

5. Weisberg S.P. et al., Obesity is associated with macrophage accumulation in adipose tissue. J Clin Invest, 2003. 112: p. 1796-1808.

6. Wisse, B.E., The Inflammatory Syndrome: The Role of Adipose Tissue Cytokines in Metabolic Disorders Linked to Obesity.J Am Soc Nephrol, 2004. 15: p. 2792-2800.

Photos courtesy of Shutterstock.

The post 4 Ways Excess Fat Makes You A Ticking Time Bomb appeared first on Breaking Muscle.

Recently researchers developed a new method for measuring body fat. The Body Adiposity Index (BAI) is a ratio of hip circumference to height. Researchers assert that hip circumference and height are strongly correlated with an individuals body fat percentage and which provides a good anthropometric measurement to create the BAI. According to researchers the BAI can be used to indicate body fat percentage for adult men and women of differing ethnicities.

This new tool can also be easily calculated by doctors or nurses with a computer or calculator. The BAI can be used in many different environments and remote locations. However, researchers note that the BAI is still in need of research and development with a wider demographic of subjects.

The post Body Adiposity Index – A New BMI? appeared first on Breaking Muscle.