In the modern world we eat more than ever before. But in spite of this surplus of calories, we may be functionally starving, because we may not be getting all that we need from the modern diet to truly thrive.
Starving for Nutrient Density
Vitamins and minerals act as co-factors for literally thousands of chemical reactions throughout the body, from facilitating the breakdown of foods into energy, through to cellular reproduction, expression of genes and much more. Suffice it to say that without enough of the ‘little guys’ of nutrition, nothing much can occur in the body. I like to think of the micronutrients (vitamins and minerals) being like the spark plugs in a car. They don’t provide the fuel directly but allow its efficient use.
United States Department of Agriculture (USDA) data shows that some fresh produce (vegetables, fruits berries) only provide around half the amounts of some vitamins and minerals that they did in the 1950s.1 To get the same amounts of nutrients, we need to eat twice the amount of some veggies and other ‘nutrient dense’ foods than we did fifty or so years ago.
In my home country of New Zealand, estimates from the Ministry of Health ‘NZ Adult Nutrition Survey’ suggest that many Kiwis are not getting the recommended amounts of many of the vitamins and minerals from their diets.2
Some of the key findings included:
- Around 20% of people fail to get sufficient vitamins A, B1, and B6.
- 8% of people fail to get sufficient B12.
- Nearly 10% of women don’t get enough iron.
- Around 25% of people don’t consume enough zinc, including nearly 40% of males.
- 45% of people don’t get enough selenium (a mineral lacking in New Zealand soils).
So we know that some of the food we eat, even if we are trying to eat a ‘good’ diet, may be less nutritious than it once was. Further, we know that we need to eat more nutrient-dense foods to supply what we require to thrive. We simply are not getting what we require day-to-day from the food we currently eat.
Even if you feel stuffed, you might not be getting all the nutrients that are lacking in the modern diet. [Photo credit: Pixabay]
Starving for Fuel
I’ll state it plainly: ‘A calorie is a calorie’ has been found to be inadequate,3 and many of our models of fuel utilisation and substrate storage are outdated. When we have a metabolic disorder or are obese, we have distorted satiety signals. We also have a reduced ability to adequately digest and assimilate some nutrients, and are unable to store and use fuels optimally. Altered satiety signals are both a causative factor and result from metabolic disorder and obesity.4, 5, 6 Thus, even if eating more than we require, we can still find ourselves lacking in readily available fuel.
It was once considered impossible to ‘starve’ while getting bigger, because in a state of caloric surplus we should have more than enough fuel. But this is not necessarily true. When we have a predisposition to store fat, we may not have sufficient fuel stored within tissue because we are unable to store efficiently. Our rates of fat utilisation can be markedly reduced, and so we have greater difficulty ‘freeing’ up fuel from fat-storage (adipose tissue). This is due to distortions in our enzymatic ability to release fat from cells and to uptake triglycerides (fats) into muscle and other cells for use. We are also at risk of becoming more and more insulin resistant, with a reduced ability to dispose of glucose, despite having developed a preference for using glucose (sugar) as fuel.
The good news is that changes in the macronutrient composition of what we eat (i.e. the relative amounts of fat vs. carbohydrate vs. protein) can positively affect weight, body-composition and cardiometabolic outcomes.
The Science of High-Protein, Low-Carb Diets
High-protein, low-carbohydrate (HPLC) diets enhance weight-loss with greater loss of body-fat and reduced loss of lean body mass due to factors including increased satiety, increased thermogenesis, muscle sparing, and improved glycaemic (blood sugar) control.7 HPLC diets have been studied for weight-loss and body composition with superior results demonstrated versus high-carbohydrate diets. Layman and colleagues compared two diets with similar fat content (~50g), one containing 68g protein and the other 125g (with the balance in both cases from carbohydrate). Participants in the higher protein group lost significantly more fat, retained more lean tissue, and reduced triacylglycerol (TAG) and increased satiety more than the lower protein group.8
Piatti and colleagues investigated the effects of two hypocaloric diets (800 kcal) in normal, glucose tolerant women, one containing 45% protein (35% carbohydrate [CHO] and 20% fat) and one containing 20% protein (60% CHO, 20% fat). Similar weight loss occurred in both groups, but retention of fat-free mass (muscle) was only seen in the higher protein diet.9 Similarly, in obese and hyperinsulinaemic women, a higher protein intake (27% vs. 16%) and similar fat intakes encouraged similar weight and fat loss with retention of lean mass only observed in the higher protein group, along with reduced TAG and improved glycaemic control versus the lower-protein, higher-carbohydrate group.10
Noakes and others have demonstrated that there may be further nutritional benefits resulting from higher protein diets: Along with a greater fat loss and reduced TAG, they observed improved B12 status compared to higher carbohydrate diets.11 In a comparison of a high-protein (30%) versus high-carbohydrate (55%) isocaloric diet (n=11), individuals on a high protein diet lost more fat with no difference observed between fat-free mass between groups.12
The positive effects of higher protein intake on body-composition can be explained due to several factors, including increased satiety and thermogenesis when compared to equivalent amounts of either carbohydrates or fat.13 Increased energy expenditure (EE) results from the formation of additional glucose from amino acids (and other substrates such as lactate and glycerol).14 There is also a higher thermic effect of feeding (TEF) (using more calories) from protein ingestion as compared to either carbohydrate or fat.15, 16, 17 Increased caloric expenditure from protein intake is not explained solely by the metabolic demands of increased gluconeogenesis and may also be accounted for by increased protein accretion in tissue, which requires greater energy expenditure than for storage of fat within adipose tissue.18 There is a large amount of both lay and scientific literature showing increased protein accretion and retention with higher protein intakes.
However, only moderate increases in protein and minor reductions in carbohydrate have not been shown to provide increased resting energy expenditure (REE) nor promote appreciably greater loss of body-fat.19 It is likely that more severe carbohydrate restriction or a much greater protein intake are the variables that promote the greatest reductions in body-fat, and in the case of high protein intakes, have the greatest effect on diet induced energy expenditure.
Higher protein intake is also considered to be more satiating than the carbohydrate it is displacing. A 2004 review by Halton and Hu found there to be convincing evidence that a higher protein intake increases thermogenesis and satiety compared to diets of a lower protein content.20
The Science Behind Low Carb-High Fat Diets
Low carbohydrate, high fat (LCHF) diets, often with low-to-moderate protein, likewise have demonstrated sufficient evidence to be considered a therapeutic option for the primary and adjunctive treatment of fatty liver disease21; type 1 diabetes22; type 2 diabetes23; some cancers24; and cognitive impairment.25
LCHF diets are likely to be superior to low-fat diets for improving several markers of cardiovascular health with the possible exception of low-density lipoprotein (LDL).26, 27, 28 But HDL-to-total cholesterol ratio appears to relate more closely to improved cardiovascular mortality than LDL levels, and this ratio is more favorably impacted by an LCHF diet in comparison to a higher carbohydrate diet.29 Beneficial lipid sub-fractions (including large particle LDL) are also increased with an LCHF diet.30
Short term studies suggest that carbohydrate restriction has the greatest effect on weight-loss, irrespective of what is substituted. For example, a 2005 randomised controlled trial by Luscombe-Marsh et al. compared a LCHP diet to a LCHF (standard protein) diet. Both yielded similar results for weight loss with little difference in other parameters (bone turnover, inflammation and calcium excretion).31
Lower-carbohydrate and higher-fat diets (not ‘LCHF’ per se) have demonstrated improved postprandial glycaemic responses and reduced insulin when compared to higher-protein, isocaloric diets.32
Does All This Mean I Should Go Low Carb?
The short answer is no. Unless of course your current high-carb diet is not working for you. We now have ample evidence that there is a wide spectrum of appropriate diets ranging from extreme low-carb (keto) diets, right through to high-carb diets, but which is best depends on activity levels and types of exercise engaged in, ethnic/genetic factors and your current metabolic state.
My advice is to ask, “Am I currently getting great results?” If you are, stick with the program! If not, a gradual carb restriction to find your appropriate dose could be beneficial. Remember that we are all unique and can find a carb intake that works best for each of us at any given phase of life. The only thing to reiterate is to eat lots of natural, fresh produce (vegetables and berries especially) to help ensure you’re getting all the little guys (vitamins and minerals) that are lacking in the modern diet.
More on the science behind nutrition:
The Best Research on Body Fat, Losing Fat, and Eating Fat
References:
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2. University of Otago and Ministry of Health. A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Wellington: 2011.
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