Does The Type of Diet You Choose Matter for Sustained Weight Loss?
Title: Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults: A Meta-analysis
Author: Johnston et al.
Objective: To determine weight loss outcomes for popular diets based on diet class (macronutrient composition) and named diet.
Obesity in American has skyrocketed in the last 60 years. In 1960, 10% of men and 15% of women were obese.Now, in 2015, more than 35% of men and women are obese. This staggering increase has been accompanied by increased incidence of diabetes, stroke, heart attack and cancer, just to name a few.
As our waistbands have thickened over the last century, so too, have the various dietary and weight loss programs designed at trimming this new weight. Some of these these have been fad diets, that have seen a quick rise and fall in popularity. Others, like the mediterranean diet and DASH diet have had more longevity.
Most of these weight loss programs are broadly available to the public through bookstores, the internet, television, social media and healthcare providers. Subsequently, there is much debate over which diet, if any, is superior to others in terms of weight loss and prevention of disease. Healthcare providers and dieticians are often asked which diet is most effective for weight loss.
And so the authors of this study used network meta-analytic approach, to assess the relative effectiveness of different popular diets in improving weight loss,
This study was a meta analysis of 48 randomly controlled clinical trials. Just to be clear, a meta analysis is the gold standard for comparing multiple different studies and combining their results into one comprehensive publication.
In order to be included, candidate studies had to include overweight or obese adults (BMI >25) randomized to a popular self-administered named diet and also report their change in weight (or BMI) at 3-month follow-up or longer.
Main outcomes were: Weight loss and body mass index at 6- and 12-month follow-up
They also classified diets based on macronutrient composition:
- Low carb: atkins, south beach, zone
- Moderate macronutrients: biggest loser, jenny craig, nutrisystem, volumetrics, weight watchers
- Low fat: ornish, rosemary conley
Ultimately, 48 unique randomized trials totaling 7286 individuals were included.
Compared with no diet, the largest weight loss was associated with
- Low-carb diets: 8.73 kg at 6-month follow-up and 7.25 kg at 12-month follow-up and
- Low-fat diets: 7.99 kg at 6-month follow-up and 7.27 kg at 12-month follow-up.
Weight loss differences between individual diets was very minimal.
Behavioral support appeared to have more impact at 6 month follow up (compared to 12 months) and exercise had more impact at 12 month follow up.
Significant weight loss of approximately 8 kg (17.5 lbs) occurred with any of the low-carb or low-fat diets.
There was minimal difference in weight loss at 6 and 12 months between individual named diets.
These results support the growing notion that net caloric intake is a larger determinant of weight loss than the macronutrient makeup of the specific diet.
It also supports the practice of choosing a diet that an individual is most likely to adhere to in the long-term in order to maintain sustained weight loss.