Early dieting predicts weight gain

159171619Teenagers who are unhappy with their weight are vulnerable to eating disorders. Big surprise. But most people probably wouldn’t guess that concerns about weight also predict which adolescents will become fatter over the next few years, as I discussed in my TEDGlobal talk.

Dr. Dianne Neumark-Sztainer heads a study at the University of Minnesota to identify risk factors for weight-related problems in teenagers. Her team studied over 2500 boys and girls in middle school or high school and again five years later.

The initial characteristics that predicted weight gain in girls during the study also predicted increases in disordered eating. The strongest predictors were a history of dieting, concerns about weight, and weight-related teasing from family. Girls whose families nagged or teased them about their weight when the study began had twice the risk of gaining weight over the next five years, compared to girls who weren’t teased.

You might imagine that the girls were already overweight, so they got teased, and then went on gaining weight. But that explanation doesn’t work because the same relationship between dieting or teasing and weight gain was found for girls who started the study at a normal weight. Similarly, a long-term follow-up of over ten thousand boys and girls born to participants in the Nurses Health Study found that frequent dieting at 9-14 years of age increased the risk of transitioning from normal weight to overweight over the next two years by a factor of 4.8 in girls and 1.7 in boys.

Why might dieting predict weight gain? One possible explanation is that food restriction leads people to binge. Indeed, teasing nearly doubled the risk of increased binge-eating among girls in the Minnesota study. Girls in the Nurses Health Study who dieted frequently were twelve times more likely to report binge eating. A third study of girls in northern California found similar results.

The deliberate cognitive control of food intake, common in dieters, may sound like a good idea, but it has several unwanted consequences. People who eat this way are heavier, on average, and more likely to gain weight over time than people who simply eat when they’re hungry and stop when they’re full. You might imagine that people adopt a controlled eating style because they have a genetic predisposition to gain weight, but that’s unlikely because the relationship holds even between identical twins.

People who ignore hunger seem to be more susceptible to external cues telling them how much to eat, such as serving size or what their friends are eating. That makes it easier for food marketers to manipulate them into overeating. And a minor dietary indulgence like eating a scoop of ice cream is more likely to set off a food binge in controlled eaters than in people who eat in response to hunger.

What’s a parent to do? By all means, talk to your kids about healthy eating. But don’t give them a hard time about their weight. Not only does that kind of talk contribute to eating disorders, but it’s also likely to make them fatter in the long run.

4 thoughts on “Early dieting predicts weight gain

  1. Wow, can’t believe I just found you. I love your work, your honesty, your scientific approach – with compassion for people as well. I am a wellness coach who primarily works with disappointed dieters. I am going to share your good work Sandra. THANK YOU!!!

  2. Just what is a diet? Does it have to be an intentional restriction of calories? When I was a teenager, I swallowed on raw egg for breakfast, had whatever was available for lunch (I lived across the street from the school and went home for lunch), and whatever my mother made for supper. I wasn’t intentionally restricting my calories. I wanted to sleep as late as possible and skipping breakfast allowed me to do that. My mother talked me into swallowing a raw egg, because she thought it was better than nothing. After getting ready for the day, I put a raw egg in a glass, drank it like I would a milkshake, and went to school.

    Did my body interpret this as a diet? Am I now suffering the consequences of this behaviour (weight gain)?

    • Dieting is intentional weight loss through food restriction. If you weren’t intentionally restricting, it’s unlikely that your behavior would lead to future weight gain. Given the wide variety of possible reasons behind weight gain – including processed foods, habitual eating, antibiotics, stress, childhood sleep loss, and prescription drugs – I wouldn’t be inclined to look toward your teenage dietary habits for an explanation.

  3. Hi Sandra, I listened and enjoyed your interview on evil sugar radio (July 2016). My comment is with regard to your stat that 100% of people with eating disorders began with a diet. I guess that could be true if your brain perceives unintended weight loss as a diet. For instance a 12 or 13 year old, not worried not concerned about weight (close to the low end of weight charts, and higher end of height charts), decides to run track/cross-country at school. Eats intuitively, even while burning more calories, has the pre-teen growth spurt and now can’t keep up with the new metabolism. Still eats when hungry, stops when full, but looses weight anyway, and is then very underweight. The eating disordered/diet thoughts, in this case started AFTER the unintended weight loss. Just semantics I guess, but I think there are many cases that were not brought on by intentional change in eating habits. I have read about kids as young as 5 that “fell into” an eating disorder. Pre-disposed, yes. Intentional dieting, no.
    My other comment has to do with the generalization of standard American diet. I think everyone has a different idea of what exactly that is, and demonizing it increases the good food- bad food mentality. For instance a family that eats mostly at home, fresh food meals may consider this “standard”. Some obsessive people or teens have interpreted this to mean they aren’t eating healthy enough, and head into the world of restrictive “lifestyles” (veg, vegan, paleo, etc.), and fall into the rabbit hole.
    Just my observations of people that I love.

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