Why diets don't work: Nobody has willpower

Why diets don't work: Nobody has willpower


Not long ago, the Atkins diet villainised carbohydrates and convinced millions to avoid starches of any kind. Today, the Paleo diet, which purports to emulate the eating habits and digestive systems of ancient humans who lived for many fewer years than people on average do today, is perhaps the most popular - or at least talked about - dietary fad. Soon there will be another fad that sweeps the dieting conversation. And another one.

Willpower problem: Diets don't work.

Willpower problem: Diets don't work.

The question that seems to hover over all this diet talk is whether any of the myriad weight loss schemes have worked. If one had, shouldn't it have survived the test of time? And if we've gone this long without a diet that has been shown to work - according to science, not simply the sellers of the fad - will there ever emerge one that actually does?

The short answer is no, according to Traci Mann, who teaches psychology at the University of Minnesota, and has been studying eating habits, self-control and dieting for more than 20 years. Over the course of her research, largely conducted at the University of Minnesota's Health and Eating Lab, Mann has repeatedly asked these sorts of questions, and always found the same disappointing answers.

Crush the cravings? Fat chance

Crush the cravings? Fat chance

Photo: Getty Images

Her findings, chronicled in her newly published book Secrets From the Eating Lab, offer a fascinating explanation for why dieting over the long term is actually impossible.

I spoke with Mann to learn what exactly it is that people misunderstand about weight, willpower, and our relationship with food. The interview has been edited for length and clarity.


A. I don't want to make it sound any less cool, but it is a lab. And it is where we do eating studies. I study eating at the lab in two basic ways: I either go out into the world, and study people and the way they eat - the way normal people do their eating - or I bring people into the lab, and put them in situations that are carefully controlled so that I can see how their eating responds to those carefully controlled situations. These two types of experiments are really opposite sides to the same coin, but you really need both. You need to see what people do in real life, and then you need some way to find out what causes what. And that's what the lab is for.





It all starts with something that suddenly struck me a while back, and that's that nobody has willpower. Everyone is blaming dieters for regaining weight they lose, and that's just wrong - it's not their fault they regain weight, and it's not about willpower, or any lack thereof.




A. What people tend to think is that if only Joe had self control then he could succeed on his diet forever. And that's not accurate, as it turns out. That's not true.


Q. What kind of biological changes?

A. There are three biological changes that take place that seem most important to me.

The first is neurological. When you are dieting, you actually become more likely to notice food. Basically your brain becomes overly responsive to food, and especially to tasty looking food. But you don't just notice it - it actually begins to look more appetising and tempting. It has increased reward value. So the thing you're trying to resist becomes harder to resist. So already, if you think about it, it's not fair.



Q. So calling it unfair doesn't even begin to describe the injustice.




A. Well, the first thing is that you can't believe anything that they say. And that's by definition, because their job isn't to tell you the truth - it's to make money. And they're allowed to lie.


Q. What would you say to someone who says "I followed or have been following so and so diet, and I've lost weight, I feel better, it's working"? What are they not understanding?


For practically any diet - crazy, or not crazy sounding - in that first six to 12 months, people can lose about 10 per cent of their starting weight. So a 90 kilogram person will lose about 9 kilograms in the short run. But the short run isn't the whole story. Everyone acts like the short run is the whole story, and that anything that happens later is the dieter's fault and not really part of the diet. People act like the only part that is the diet's fault is the beginning bit. The long term part, people always say that's not the diet, that's the person. And yet, it's clear that that's not true. It's over the long term that you see all these biological changes take control.


A. An idea that I want to float, if I might, is that will power is actually a very different thing when you talk about eating. Will power can be extremely useful in certain parts of people's lives. But when it comes to eating, it's just not the problem. It's not the fix.


Let's say you're in a meeting, and someone brings in a box of donuts. If you're dieting, now you need to resist a donut. That is going to take many, many acts of self-control. You don't just resist it when it comes into the room - you resist it when you look up and notice it, and that might happen 19 times, or 90 times. But if you eat it on the 20th time, it doesn't matter how good your will power was. If you end up eating it, you don't get credit for having resisted it all those times. In virtually any other arena, that would be an A+, but in eating that's an F.





Q. So people should feel comfortable just as they are? That seems like a pretty tough truth to swallow.

A. If you think about it, people do drop below their set range and stay there. A small percentage of dieters - something like 5 per cent - can do it. And they do do it. But they do it by devoting every minute of their life to staying at that weight. Basically, they spend their entire life living like a starving person, fighting biology, and evolution. And to me that seems wrong.


What's really sad to me is that it isn't just society blames dieters when they gain weight. Dieters blame themselves, and I really think that that's a shame. They're in a situation where food looks more tempting, they're hungrier than they should be, their body is getting by on fewer calories, and everything is just working against them. And yet people are always so quick to say "well, it was their hand holding the fork."


The Washington Post