The Atkins diet may produce short-and-long-term weight loss in overweight and obese adults

Anton S, Hida A, Heekin K, et al. Effects of popular diets without specific calorie targets on weight loss outcomes: Systematic review of findings from clinical trials Nutrients. 2017;9:E822.

Review question

What short-and-long-term effects do popular diets have on weight loss in overweight and obese adults, when conducted in their original format without calorie targets, meal replacements, commercial products, or structured exercise programs?

Background

Alternative diets have become increasingly popular in recent years despite questions regarding their effectiveness being raised by experts, researchers, and health professionals. A previous meta-analysis on the effectiveness of popular diets found that differences between the diets were small, and that weight loss was mainly prompted by calorie reduction. However, this analysis included studies which told participants to be more physically active and/or lower their intake of calories beyond the recommendations of the popular diet being investigated. To date, there has been no evaluation of the effectiveness of certain popular diets without calorie goals or structured physical activity.

How the review was done

This is a systematic review of 16 clinical trials published between 2003 and 2015, including a total of 1261 participants.

• For diets to be included in the review, they had to have been tested by clinical trials that: were in English, looked at adults with a body mass index ≥25, had at least 15 participants, and measured weight loss objectively.    
• Participants were overweight or obese adults between 18 and 70 years of age.
• Study participants took part in a study evaluating one of the following popular diets: Atkins (low-carb and no animal proteins), Dietary Approaches to Stop Hypertension (DASH –  focus on complex carbs, lean protein, low-fat dairy, fruits, and vegetables); Glycemic-Index (focus on foods that cause lower rises in blood sugar levels at a slower rate); Mediterranean (focus on complex carbs and healthy fats with less red meat, sugar, and saturated fat); Ornish (vegetarian diet with 10% of calories coming from fat); Paleolithic (emphasis on meats, fruits and vegetables and no refined sugar, diary and grains); or Zone (40% carbs, 30% protein, and 30% fat) for periods of 3-24 months.
• Researchers measured change in the participants’ weight in the short-term (≤ six months) and/or long-term (≥ one year) to determine clinically significant weight loss.

What the researchers found

Thirty-eight popular diets were listed in the 2016 U.S. News & World Report, of which 20 met the criteria needed to be include in the review. From these 20 eligible diets, only seven (Atkins, DASH, Glycemic-Index, Mediterranean, Ornish, Paleolithic, and Zone) were evaluated by clinical trials in their currently recommended form, and for most only a small number of studies had been conducted, which made it difficult to form definitive conclusions. Of the seven popular diets tested, Atkins was evaluated most often.

Clinically meaningful effects on short-and long-term weight loss were observed for the Atkins, Paleolithic, and Mediterranean diets, although for the Paleolithic and Mediterranean diets, the evidence was limited to only one study for each outcome. The DASH, Glycemic-Index, and Ornish diets were not associated with meaningful weight loss either in the short or long-term, while the Zone diet showed mixed results for short-term weight loss and no effect in the long-term. Furthermore, several studies reported that participants had a difficult time sticking to their diets, and only a small number of participants continued with their diets following the study. More research is needed to develop a better understanding of the safety of these diets, and their impact on weight loss in both the short-and-long-term.

Conclusion

The Atkins diet may produce short-and-long-term weight loss in overweight and obese adults. More research is needed to evaluate the safety of Atkins, as well as the effectiveness and safety of other popular diets.