Sunday, 4 March 2018

Do We Need Better Diets?

Do We Need Better Diets?
Maybe most dieting is ineffective because we’re doing it wrong somehow. Many people believe that only a certain type of diet (low carbohydrate, low fat, intermittent starvation, or whatever) causes people to lose weight permanently.

However, clinical studies do not support this belief. In head-to-head comparisons, diets that provide the same number of calories through different types of food result in similar weight loss and regain.

Certain individuals may find a particular diet easier to follow than others, but there’s no evidence that any of them can permanently lower the brain’s defended range.

Maybe if we lost the weight more slowly, we could keep it off. No evidence supports this common belief either, despite its intuitive appeal.

One year after weight loss, there was no difference in outcome between people who had lost their weight quickly and those who had lost it slowly. 

Some point to snacking as a possible culprit. But there’s not much research to back up that belief. In one randomized controlled trial (the gold standard for intervention studies), being required to eat snacks had no effect on people’s weight because they ate less at meals to compensate, as a weight thermostat should cause them to do.

In addition, observational studies do not show any association of weight gain with eating between meals.

Perhaps the problem is taking a short-term approach to weight loss, instead of focusing on permanent lifestyle changes.

Unfortunately, while temporary changes do produce temporary results, the long-term effects of weight loss programs are disappointing even with persistent support.

The Diabetes Prevention Program provided individual coaching for three years, with one coach per twenty dieters.

The coach delivered an initial sixteen-session curriculum, followed by group classes and motivational campaigns, along with interventions tailored to remove barriers identified by each person.

Supervised exercise sessions were offered twice a week. With all this attention, the participants lost an average of fifteen pounds by the end of the first year and had regained almost all of it five years later, leaving them an average of four pounds lighter. 

The Look AHEAD program had similar results. This state-of-the-art behavioral weight-loss trial compared standard lifestyle advice for diabetics with an intensive intervention in more than five thousand overweight or obese patients who already had type 2 diabetes (the kind that’s related to obesity) when the study started.

The intensive program was well named, providing patients with more than three hundred contacts with dietitians, psychologists, and exercise specialists over eight years. It started with 108 group or individual sessions in the first year, continued with 24 sessions and 12 phone calls per year for years two through four, and ended with 24 sessions per year in years five through eight.

In an unusual twist, even the control group lost a bit of weight by the end of the study, perhaps because of the motivation provided by having diabetes or the researchers’ decision to prescreen participants for compliance with instructions.

With all that effort and expense, after the eighth year, the intensive group had lost an extra 2.6 percent of their body weight, so they weighed 5.7 pounds less, on average, than the controls.

About the same number of people gained weight over the study (26.4 percent) as lost at least 10 percent of their weight (26.9 percent). Those are the best long-term results ever reported for a behavioral weight-loss program, and they are underwhelming to say the least.

In short, the problem isn’t that we’re dieting the wrong way. It’s that dieting isn’t getting us anywhere.

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