Macronutrients Don’t Matter: Comparison of 4 Weight Loss Diets

Low-carb, low-fat, high-protein – every diet seems to have a theory on what is best for weight loss. But what actually IS best? Science says macronutrient ratios don’t matter after all.

The formula for weight loss is pretty simple: fewer calories consumed + more calories expended = loss of body weight (tissue). Simple to understand, but difficult to do. Difficult because:

The formula for weight loss is pretty simple: fewer calories consumed + more calories expended = loss of body weight (tissue). Simple to understand, but difficult to do. Difficult because:

  • We live in a world where calories abound. They’re inexpensive and abundant.
  • Many lack discipline. Over-consuming calories when one does not really need them seems to be a hobby for many.
  • A sedentary lifestyle. Sitting for hours in front of a computer or television, riding the escalators versus taking the stairs, driving as opposed to walking. Many simply do not move enough during the day.

Regardless of the root-cause of weight gain, when one attempts to lose that weight, both fat and lean mass can go. Ideally, we want to target the former and preserve the latter because muscle (lean) tissue is metabolically active. So a question is: can one’s macronutrient intake (carbohydrates, protein, and fat) be structured to better preserve lean tissue?

A study in The New England Journal of Medicine was performed to determine whether fat and lean tissue changes were influenced by the composition of carbohydrates, proteins, and fats in one’s diet. They administered energy-reduced diets with varying amounts of each macronutrient to 811 overweight adults assigned to one of four groups (defined by percentages of fat, protein, and carbohydrates):

  • 20% – 15% – 65 %
  • 20% – 25% – 55%
  • 40% – 15% – 45%
  • 40% – 25% – 35%

All diets were composed of similar foods and met guidelines established for cardiovascular health. The participants were offered group and individual instructional sessions for two years. The primary outcome was the change in body weight after two years in two-by-two factorial comparisons of:

  • Low fat vs. high fat
  • Average protein vs. high protein
  • Both of the above compared to the highest and lowest carbohydrate content

Six months into the study, the average participant lost 13.2 pounds. This represented 7% of their initial body weight. At the one year point, most began to regain body weight.

Similar for those assigned to both the 15% and 25% protein (6.6 and 7.9 pounds).

Exactly the same for those in the 20% and 40% fat groups (7.3 pounds).

The 65% and 35% carbohydrate groups were 6.4 and 7.5 pounds of weight loss, respectively.

Other important findings:

  • Of the 80% of participants who completed the study the average weight loss was 8.8 pounds.
  • 14 to 15% of the participants reduced their initial body weights at least 10%.
  • Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets.
  • Attendance was strongly associated with weight loss. It averaged out to .44 pounds lost per session attended.
  • All diets improved lipid-related risk factors and fasting insulin levels.

What can be gleaned from this study? The researchers concluded that any reduced-calorie diet results in clinically meaningful weight loss. It does not matter what the percent breakdown of macronutrients is.

The Acceptable Macronutrient Distribution Ranges (AMDR) of carbohydrates at 45-65%, fats at 20-35%, and protein at 10-35% has been proven reasonable, based on your strength-conditioning/sport-specific needs. What is more significant is your goal of weight loss, maintenance, or gain:

  • Reduce calories + increased energy expenditure = weight loss
  • Equal balance between calories in vs .calories out = weight maintenance
  • Increase calories + decreased energy expenditure = weight gain

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