- While current research comparing diets of differing macronutrient ratios may not point to one “perfect” diet, there is compelling research about certain dietary styles, including the Mediterranean diet, that offers strong guidance.
- Curious about “quick fixes” like diet pills and gastric bypass surgery? Check out our tips for how to reach a winning weight.
While low-fat was once the diet du jour, subsequent research has shown that low-fat diets are ineffective, and moreover, that eating healthy fats is beneficial for health.
- In the United States, obesity has become increasingly common even as the percentage of fat in the American diet has declined from 45 percent in the 1960s to about 33 percent in the late 1990s. So, cutting fat is not shrinking waistlines. (27, 28)
- Experimental studies lasting one year or longer have not shown a link between dietary fat and weight. (29, 30)
- In the eight-year Women’s Health Initiative Dietary Modification Trial, women assigned to a low-fat diet didn’t lose or gain more weight than women eating their usual fare. (31)
Low-carbohydrate and Mediterranean diets can be effective
While many “diets” are fads meant to be followed for short periods of time, research shows that some approaches, including some low-carbohydrate diets and Mediterranean diets can be good models upon which to base your own dietary strategy as long as they incorporate healthy, high-quality foods.
One study comparing a low-carbohydrate, low-fat, and Mediterranean diet followed over 300 people for a 2-year period and found that diets composed of different foods can lead to different weight loss outcomes. Published in the New England Journal of Medicine, this study concluded that:
- Mediterranean and low-carbohydrate diets might be more effective than low-fat diets.
- The positive effects of the low-carbohydrate diet and the Mediterranean diet upon lipids and glycemic control suggest that individualized dietary interventions – which take personal preferences and metabolic considerations into account – could be effective. (32)
A 2013 study on the effects of a Mediterranean diet on cardiovascular disease showed that among patients at high risk for CVD, a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events over 4.8-years of follow-up. (33)
- This was the first randomized trial that showed reduced cardiac events over a long follow-up period, so it provided strong scientific evidence that the Mediterranean diet is a heart-healthy dietary approach.
- Though this study focused on cardiovascular outcomes rather than weight loss, it still provides solid evidence that “a calorie is a calorie” is not the case, and that instead, food quality is a key contributor to personal health.
- It also shows that low-fat diets are continuing to lose credibility, and that incorporating healthy fats – such as those included in the Mediterranean diet – can improve heart health and weight loss.
What exactly is a “Mediterranean” Diet?
There isn’t one exact Mediterranean diet, as this eating style takes into account the different foods, eating patterns, and lifestyles in multiple countries that border the Mediterranean Sea. However, there are similarities that define a Mediterranean eating pattern. As described by a 2013 study (33), the traditional Mediterranean diet includes:
- High intake of olive oil (preferably extra virgin), nuts, vegetables, fruits, and cereals
- Moderate intake of fish and poultry
- Low intake of dairy products, red meat, processed meats, and sweets
- Wine in moderation, consumed with meals
Conclusion: The best diet incorporates high-quality foods in appropriate portions; there isn’t one “perfect” diet for everyone.
Calories matter, but quality is equally important. When making dietary decisions, regardless of whether you choose a certain dietary style such as low-carbohydrate or Mediterranean, you can also use the Healthy Eating Plate as a guide for how to fill your plate.
A healthy diet for weight loss also needs to be sustainable, and regardless of what you’re eating, you need to make sure you’re not eating too many calories overall. Calories do matter, but focus first on choosing high-quality, healthy foods.
27. Is total fat consumption really decreasing, U.C.f.N.P.a. Promotion, Editor. 1998.
28. Diet and Health: Food Consumption and Nutrient Intake, U.D.o.A. Economic Research Service, Editor. 1977–1996.
29. Willett, W.C., Dietary fat plays a major role in obesity: no. Obes Rev, 2002. 3(2): p. 59-68.
30. Willett, W.C. and R.L. Leibel, Dietary fat is not a major determinant of body fat. Am J Med, 2002. 113 Suppl 9B: p. 47S-59S.
31. Howard, B.V., et al., Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial. JAMA, 2006. 295(1): p. 39-49.
32. Shai, I., et al., Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med, 2008. 359(3): p. 229-41.
33. Estruch, R., et al., Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med, 2013. 368(14): p. 1279-90.
The aim of the Harvard T.H. Chan of Public Health Nutrition Source is to provide timely information on diet and nutrition for clinicians, allied health professionals, and the public. The contents of this Web site are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Web site. The information does not mention brand names, nor does it endorse any particular products.