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Fad diets

December 2003

With the holidays fast approaching the ever-present battle of the bulge looms large with visions of holiday treats and festive meals. Undoubtedly, millions of Americans are either thinking about dieting preemptively to lose a few pounds so they can enjoy the bounty, or trying to decide which diet to get on after the holidays to shed the inevitable weight gained. Thankfully, timely research sheds some helpful light on dieting.

The results of a recent head-to-head comparison of the four biggest diets of last year are finally in. Atkins, Dean Ornish, Weight Watchers and the Zone diets squared off in a one-year “battle of the bulge” to see which diets worked the best and what effects the diets had on cholesterol and cardiovascular risk factors. The findings were reported at the American Heart Association’s annual symposium in November.

The study included participants ranging in age from 22 to 72, and they all had at least one risk factor for heart disease (e.g. high blood pressure, high cholesterol or blood sugar). The average weight of the participants was about 216 lbs. for someone 5’ 6” tall, which meets the accepted criteria for obesity. The participants were asked to follow one of the four diets for one full year, after which the effects were measured.

The Atkins diet is a low-carbohydrate, high-protein diet. Dean Ornish’s diet is a vegetarian-based, low fat, high fiber diet. Weight Watcher’s is a low fat, moderate calorie diet that works on the point system. Finally, the Zone diet promotes proportions of 40% carbs, 30% protein and 30% fat at each meal.

First, the good news… all participants lost weight no matter which diet they adopted. The bad news was that the weight loss at the end of one year was small – only about 3%, or about 6 lbs. for a 200-lb person. Weight loss was partly blunted by the fact that about half of the participants in both the Atkins and Ornish diets dropped out before one year, and about 1/3 of those on the Weight Watchers and Zone plans dropped out. For those who stuck with their diet for the full year, weight loss ranged from about 4% for the Atkins group, to about 6% for the Ornish group.

Probably the best news is that all four groups experienced a significant reduction in cardiovascular risk factors. This meant a drop in LDL (“bad”) cholesterol, a rise in HDL (“good”) cholesterol, and a reduction in insulin levels.

So which diet was “the best”? Well, it’s not entirely scientific, but here’s a brief summary:

• Ornish produced the greatest weight loss and the greatest cardiovascular risk reduction (CVRR), but only half of the people could stick with the diet. If you have a heart condition already, this may be the best diet to stick to.
• The Zone produced a similar CVRR to Ornish, but with less weight loss. This program had the highest CVRR per pound lost. Plus, 2/3 of participants were able to stick with the Zone diet. Overall, the Zone was the “best bang for the buck”, in both allowing people to stick with it while reducing cardiovascular risk.
• Weight Watcher’s was closely behind the Zone in producing weight loss and CVRR while retaining 2/3 of participants.
• Atkins fared the worst, with the lowest CVRR and low retention, as well as the least weight lost.

However, because all of the diets were successful to a degree, and weight loss overall was modest at best, it’s hard to pick a clear winner here – the Zone may have a slight edge overall. The Zone also produced the most CVRR per pound of weight lost, so from that standpoint it may be the most efficient diet at lowering cardiovascular risk. But the take home message here is that no one single diet program was head and shoulders above the others.

The most important take-home lessons from this yearlong study, in my opinion, are the following:

• Significant weight loss is a long-term process that requires a lifelong commitment and a permanent change in eating behavior, not a temporary change.
• Weight loss accomplished by any means produces a meaningful reduction in cardiovascular risk factors for overweight individuals.
• There’s no clear “winner” when it comes to low-carb vs. low fat – all diets fulfilled the objectives of promoting weight loss while reducing cardiovascular risk. Even the low-carb, relatively high fat Atkins’ diet seemed to reduce cardiovascular risk factors.
• The end result - weight loss - is more important the means of promoting it.

Mark Liponis, MD © 2003