Does one diet have a benefit over another diet?

  • The short answer no. One diet may have a benefit for some people but not everyone. One type of diet may not be effective for everyone due to individual differences in genes and lifestyle.
  • There are a lot different types of diets that we hear about, they usually differ depending on the percentage of one macro-nutirent compared to another

What are macronutrients ?

a type of food that is required in large amounts in the human diet.

  • Carbohydrates,
  • Proteins
  • Fats

The Harvard TH School of Public healths website states “Researchers have begun comparing these “macronutrient management”-style diets to one another in order to determine which is most effective, but thus far evidence is largely inconclusive.”

  • “the percentage of calories from fat, protein, and carbohydrate do not seem to matter for weight loss.”
  • “Low-fat diets have long been touted as the key to a healthy weight and to good health. But the evidence just isn’t there.”


  • Some studies did show that increased consumption of healthy fats-monounsaturated and polyunsaturated fat was not associated with weight gain where as consumption of trans fats were.
  • Mono-saturated fats found in  olives and avocados can help lower the bad cholesterol.
  • Poly unsaturated fat found in fish can also decrease the bad cholesterol.
  • Consider eating a diet that higher in healthy fats compared to trans fats.
  • According to the American Heart Association, “The primary dietary source for trans fats in processed foods is “partially hydrogenated oils.”
  • Trans fats have been linked to heart disease,  stokes and diabetes.


High protein diets offer benefits short term but in long term studies support that they do not perform any better than the other types of diets

According to the Harvard TH School of Public health, a high protein diets offers some benefits,

  •  You tend to feel fuller on fewer calories compared to carbohydrates.
  • It takes more energy to metabolize and store protein compared to the other macronutrients.
  • Protein is needed to maintain lean muscle mass.
  • Consider lean meats over red or processed meat which have been shown to increase the risk of heart disease.
  • Consider eating nuts, beans, fish, or poultry.
  • There are studies to support that a modest increase in protein content and a modest reduction in the glycemic index led to an improvement in maintenance of weight loss. (Reference  Larsen, T.M., et al., Diets with high or low protein content and glycemic index for weight-loss maintenance. N Engl J Med, 2010. 363(22): p. 2102-13.)


  • Processed carbohydrates such as white bread, pastas and rice have a high glycemic index.
  • When you eat these types of foods your blood sugar and insulin levels increase.
  • Long term studies do support that diets higher in whole wheat, brown rice, barley have been shown to help maintain weight.
  • Whole grains increase blood sugar slowly and we do not see the dramatic spikes as we do with processed carbohydrates.
  • Examples of whole grains include whole-wheat flour, bulgur (cracked wheat), oatmeal, whole cornmeal, and brown rice.

What do some studies show about the different types of diets

High fat Diets verse carbohydrate diet

  • A study published in JAMA in 2007 showed that a high fat diet reduced weight more so than other types of diets  However follow up studies did not support a benefit of a high fay diet. In addition, there is concern for an increased risk of heart disease with greater consumption of trans fats.

Low fat diet verse high or low protein diet

  • Studies comparing the long-term effects of low fat diet with either a high or low protein content did not show a  significant differences in weight loss.

High protein verse high carbohydrate

  • The high protein diet resulted in better weight loss results after three months. Note this study does not include any long term results. Reference Claessens M, van Baak MA, Monsheimer S, Saris WH. The effect of a low-fat, high-protein or high-carbohydrate ad libitum diet on weight loss maintenance and metabolic risk factors. Int J Obes (Lond) 2009; 33:296.

Mediterranean Diet 

  • Weight loss was greater with the Mediterranean and low-carbohydrate diets compared to a low-fat diet.
  • A Mediterranean diet has been shown to decrease the risk of type 2 diabetes,

Low carbohydrate Diet

  • Low carbohydrates lose weight faster then low fat diets but the results are only short term, these results were not sustained at 1 year. Nordmann AJ, Nordmann A, Briel M, et al. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med 2006; 166:285.
  • A low carbohydrate diet can increase high-density lipoprotein [HDL] and decreased triglycerides.

Vegetarian Diet 

Research shows that people who follow a vegetarian eating plan, on average, eat fewer calories and less fat than non-vegetarians. Some research has found that vegetarian-style eating patterns are associated with lower levels of obesity, lower blood pressure, and a reduced risk of heart disease.Reference

Bottom line

  • There is wide variation in weight loss among these different trials. The most important aspect is adherence to a diet rather than the type of diet.
  • Weight loss differences between individual diets were minimal. Those who attended support groups did better with their weight loss attempts.
  • Consider “high-quality foods”  which include lean meats, vegetables, whole grains and healthy fats.

Reference Sacks FM, Bray GA, Carey VJ, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med 2009; 360:859.

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Copyright © 2011, Harvard University. For more information about The Healthy Eating Plate, please see The Nutrition Source, Department of Nutrition, Harvard School of Public Health,, and Harvard Health Publications,

World health organization resting metabolic rate (RMR) and calculation of daily energy requirement.

What are some of the different types of diet

High fat-Atkins,Protein Power, South Beach,Mediterranean Diet

High Protein-Zone, Sugar Busters

Carbohydrate diets Ornish, Pritikin, Mayo clinic, ADA


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