Battle of the Bulge…

Obesity continues to reach epidemic proportions in developed nations. For people who suffer from obesity, choosing a diet that not only works but one that they are capable of adhering too can be a difficult challenge. A very recent study, published in the New England Journal of Medicine (Shai et al, 2008), compares the results of 3 popular diets in moderately obese subjects over a period of two years.

METHODS:

322 moderately obese were randomly assigned to one of three diets:

• low-fat, restricted-calorie
• Mediterranean, restricted-calorie
• low-carbohydrate, non-restricted-calorie

Low-Fat Diet

“The low-fat, restricted-calorie diet was based on American Heart Association guidelines. We aimed at an energy intake of 1500 kcal per day for women and 1800 kcal per day for men, with 30% of calories from fat, 10% of calories from saturated fat, and an intake of 300 mg of cholesterol per day. The participants were counseled to consume low-fat grains, vegetables, fruits, and legumes and to limit their consumption of additional fats, sweets, and high-fat snacks.”

Mediterranean Diet

“The moderate-fat, restricted-calorie, Mediterranean diet was rich in vegetables and low in red meat, with poultry and fish replacing beef and lamb. We restricted energy intake to 1500 kcal per day for women and 1800 kcal per day for men, with a goal of no more than 35% of calories from fat; the main sources of added fat were 30 to 45 g of olive oil and a handful of nuts (five to seven nuts, <20 g) per day. The diet is based on the recommendations of Willett and Skerrett.”

Low-Carbohydrate Diet

“The low-carbohydrate, non–restricted-calorie diet aimed to provide 20 g of carbohydrates per day for the 2-month induction phase and immediately after religious holidays, with a gradual increase to a maximum of 120 g per day to maintain the weight loss. The intakes of total calories, protein, and fat were not limited. However, the participants were counseled to choose vegetarian sources of fat and protein and to avoid trans fat. The diet was based on the Atkins diet.”

RESULTS:

“The Mediterranean-diet group consumed the largest amounts of dietary fiber and had the highest ratio of monounsaturated to saturated fat (P<0.05 for all comparisons among treatment groups).”

“The low-carbohydrate group consumed the smallest amount of carbohydrates and the largest amounts of fat, protein, and cholesterol and had the highest percentage of participants with detectable urinary ketones (P<0.05 for all comparisons among treatment groups).”

WEIGHT LOSS:

Mean weight loss was (total) [participants who completed study]:

• 2.9 kg for the low-fat group [3.3kg]
• 4.4 kg for the Mediterranean-diet group [4.6Kg]
• 4.7 kg for the low-carbohydrate group [5.5kg]

Maximum weight reduction was achieved during the first 6 months of this study; this period was then followed by the maintenance phase of partial rebound and finally a plateau phase.

CHOLESTEROL REDUCTION:

“The relative reduction in the ratio of total cholesterol to high-density lipoprotein cholesterol was 20% in the low-carbohydrate group and 12% in the low-fat group (P=0.01).”

DIABETIC PARTICIPANTS:

“Among the 36 subjects with diabetes, changes in fasting plasma glucose and insulin levels were more favorable among those assigned to the Mediterranean diet than among those assigned to the low-fat diet (P<0.001 for the interaction among diabetes and Mediterranean diet and time with respect to fasting glucose levels).”

CONCLUSIONS:

“Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets. The more favorable effects on lipids (with the low-carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions.”

SUMMARY:

Additionally, irrespective of which diet which the participants were randomized to, the weight loss peaked at just 6 months.  Afterward, there was a slight rebound in weight gain which was followed by a plateau phase.

To those who are seeking to lose weight, this suggests that dietary interventions alone may not be the best option.  Choosing the optimal diet along with both an exercise program as well as a strategy to stay focused and adherent to both is more successful long-term approach.

Reference:

1. Shai I, Schwarzfuchs D, Henkin Y, Shahar DR, Witkow S, Greenberg I, Golan R, Fraser D, Bolotin A, Vardi H, Tangi-Rozental O, Zuk-Ramot R, Sarusi B, Brickner D, Schwartz Z, Sheiner E, Marko R, Katorza E, Thiery J, Fiedler GM, Blüher M, Stumvoll M, Stampfer MJ; Dietary Intervention Randomized Controlled Trial (DIRECT) Group. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. 2008 Jul 17;359(3):229-41.