Popular Diets Analyzed for Effectiveness

Low carb dieters lost the most weight but there was little difference between popular eating plans

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Whether deciding to cut out carbs, reduce fat, count calories or adopt the latest fad, picking the right diet plan can be a tough call to make. Researchers recently studied some common diets to see which ones were the most effective.

The authors of a recent study looked at data on common named diets, such as Nutrisystem, Weight Watchers and Jenny Craig.

They found that low-carb diets were best for weight loss, but the differences between the diets were small.

"Talk to a nutritionist about finding a safe, healthy diet."

The study was written by Bradley Johnston, PhD, of the Hospital for Sick Children Research Institute and the University of Toronto in Ontario, Canada, and colleagues.

The research team set out to examine numerous name-brand diets for effectiveness at helping obese people lose weight.

Patients were considered overweight if they had a body mass index (BMI) of 25 or greater. BMI is a calculation of body composition made using height and weight.

The researchers studied low-carb diets like Atkins, South Beach and Zone; low-fat diets Ornish and Rosemary Conley; and moderate macronutrient diets Biggest Loser, Jenny Craig, Nutrisystem, Volumetrics and Weight Watchers.

Dr. Johnston and colleagues conducted what’s called a meta-analysis, taking data from 48 past trials with 7,286 participants total.

The authors found that the most weight loss was associated with low-carb diets — an average of 19.25 pounds lost after six months.

Patients on low-fat diets lost an average of 15.43 pounds in the same time frame, the authors found.

Patients on the popular Atkins diet, which limits carbs and emphasizes proteins and fats, lost an average of 3.77 pounds more than those on the Zone diet, another low-carb, high-protein diet.

Many diets appeared effective, the authors noted.

“There is no need for a one-size-fits-all approach to dieting because many different diets appear to offer considerable weight loss benefits,” the authors wrote.

The authors noted that, because it’s tough to stick to diets, especially those that restrict cravings for carbs or fats, patients can choose what works best for them.

“Although our study did not examine switching between diets, such a strategy may offer patients greater choices as they attempt to adhere to diet and lifestyle changes,” they wrote.

In an editorial about the research, Linda Van Horn, PhD, RD, called for further study of not just weight loss between diets but also nutrient quality, long-term patient outcomes and energy intake.

She wrote that the findings “underscore the importance of effective diet and lifestyle interventions that promote behavioral changes,” to reduce calories and eat nutritious foods.

In an interview with dailyRx News, Jane Sadler, MD, family medicine physician at Baylor Medical Center at Garland in Garland, Texas, explained her diet recommendations to patients trying to lose weight.

"First of all, I let patients know that studies have shown improved weight loss success with professionally run nutritional programs such as Weight Watchers (who have the best long-term success) or other centers including Jenny Craig, Medi-Fast, etc.," Dr. Sadler said.

"In addition, we know that low-carb diets such as the Atkins Diet have the greatest weight loss success," she said. "However, a combination of diets usually works best for most. Including a flexitarian diet with a low carb-diet has worked for many of my patients. By eating meats less than two times weekly, patients are motivated to eat more greens and put more color on their plate. Result: improved nutrition and less caloric intake!"

Dr. Sadler also had some general recommendations for individuals who are trying to lose weight.

First, she recommended, have an accountability partner. "This could be your physician, advanced practioner or a registered dietician. It should not be a friend or family member as the close personal relationship could be at risk should the diet be unsuccessful." Second, she recommended being flexible with dieting. "Alternate low-carb with high-protein diets or use a combination," she said. "Go meat-free for several days (flexitarian)."

Dr. Sadler said she tells patients who want to lose weight to exercise at least 160 minutes a week. She also recommended low impact exercises, such as yoga and walking, to lower adrenal stress. Lower stress, said Dr. Sadler, can help with the ability to lose fat and relax.

The study and editorial were published online Sept. 2 in JAMA.

The Canadian Institute of Health funded the research. The authors did not disclose any conflicts of interest.

Review Date: 
September 3, 2014
Last Updated:
September 8, 2014