Q: Despite all the claims of weight loss diets, why don’t most of them work?
A: More than a third of Americans are on a specific diet, with weight loss as a leading reason. Most will be disappointed: Even when successful, lost weight is frequently regained within a few months.
Why is this so? Some people don’t follow their diets carefully and never lose much weight. Others may abandon the diet after a while, because the foods aren’t appealing. Some may engage in less physical activity as they consume fewer calories.
Whatever the reasons, popular diets may be modestly effective for a while, but, as demonstrated by a new study, benefits are largely gone within a year.
Researchers analyzed 121 trials that enrolled nearly 22,000 overweight or obese adults following one of 14 popular diets for an average of six months, including the Atkins diet, Weight Watchers, Jenny Craig and the Mediterranean diet. The diets were grouped into three categories: low-carbohydrate, low-fat, and moderate-macronutrient (this last group was similar to the low-fat group, but with slightly more fat and slightly less carbohydrate).
Here’s what they found:
-- Low-carbohydrate and low-fat diets both resulted in weight loss of about 10 pounds at six months, but most of the lost weight was regained within one year. People in the moderate macronutrient group tended to lose less weight than those following the other diets.
-- Blood pressure and cholesterol results improved modestly at six months, but generally returned to where they started after a year. One exception was noted: reduced LDL (“bad”) cholesterol levels on the Mediterranean diet persisted at one year.
-- There were no major differences in other health benefits between the various diet programs.
Based on this new report, you might be tempted to give up on weight-loss diets. But here’s another perspective: it probably matters less which specific diet you pick than whether you stick with it.
The average duration of the studies included in this analysis was six months. What if they’d lasted 12 months or longer? The benefit would likely have been greater and more long-lasting. The trick is to pick a diet with foods you actually like so that it’s not hard to stick with it.
And, there are factors other than diet that can have a big impact on weight. For example, physical activity and sleep are important.
Rather than following a highly restrictive diet, I endorse the Mediterranean diet. It’s among the best studied, performs well when compared with other diets, and was the only diet in this analysis to have long-lasting effects on LDL cholesterol levels.
If you’re struggling with your weight, talk to your doctor, a nutritionist, or perhaps a health coach. Together, decide on dietary and other lifestyle changes that appeal to you. Then stick with them!
(Robert H. Shmerling, M.D., is a senior faculty editor at Harvard Health Publishing and corresponding member of the Faculty of Medicine at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)
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