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The Effectiveness of Different Diet Programs on Weight Loss

Weight loss outcomes are comparable among named diet programs…. 

There are many named or branded weight loss programs available to the public through books and online or in-person support. Some claim to be superior to another for inducing weight loss; however, which diet program is the best remains unclear.

In a randomized, parallel-group study published in the Annals of Internal Medicine, Dr. Lydia Bazzano and a team of researchers assessed the effects of low-carbohydrate diet compared to low-fat diet in 148 men and women. The results of the study revealed that low-carbohydrate diet was more effective for weight loss and cardio risk factor reduction than low-fat diet. At 12 months, participants on the low-carbohydrate diet experienced a greater reduction in weight (mean difference = -3.5kg; P = 0.002), fat mass (mean difference = -1.5%; P = 0.011) and ratio of total HDL (mean difference = -0.44; P= 0.002) compared to those on low-fat diet.

In a recent study published in JAMA, Bradley C. Johnson, PhD, from the Hospital for Sick Children Research Institute in Toronto, Canada, and colleagues performed a meta-analysis of randomized clinical trial data to assess the relative effectiveness of different named diets in improving weight loss. The authors looked at 59 articles with 48 randomized trials (including 7186 individuals with median age of 45.7 years and median weight of 94.1kg). Forty three trials reported weight loss at 6 months follow-up, and twenty-five trials reported weight loss at 12-months follow-up.

At 6-month follow-up, all diets were superior to no diet. Low-carbohydrate diets had a median difference of 8.73kg in weight loss (95%CI 7.27-10.20), and low-fat diets had a median difference of 7.99kg in weight loss (95%CI 6.01-9.92) compared to no diet. In addition, low-carbohydrate diet class was 83% more superior to other diet classes, except for low-fat diet class. At 12-month follow-up, the median weight loss was 1 to 2 kg less than after 6-month follow-up.

According to Dr. Johnson, "although statistical differences existed among several of the diets, the differences were small and unlikely to be important to those seeking weight loss. This supports the practice of recommending any diet that a patient will adhere to in order to lose weight."

Practice Pearls:
  • Low-carbohydrate and low-fat diets could result in significant weight loss compared to no diet.
  • Weight loss outcomes are similar among named diet programs.
  • The best diet is the diet the patient will adhere to.

Bazzano L, Hu T, Reynolds K, et al. Effects of low-carbohydrate and low-fat diets: A randomized trial. Ann Intern med. 2014; 161(5):309-318.

Johnston B, Kanters S, Bandayrel K, et al. Comparison of weight loss among named diet programs in overweight and obese adults: A meta-analysis. JAMA. 2014; 312(9):923-933.