Why 'moderation' is the worst weight-loss advice ever

Weight loss is, for most people, a toggle between diet and not-diet.
Weight loss is, for most people, a toggle between diet and not-diet.  Photo: iStock


"Just eat everything in moderation." Anyone who's trying to lose weight hears it all the time, along with its cousins: Eat less, move more; eat fewer kilojoules than you expend.

Sure, fine, good, yes. All that is true. But if I could do that, do you seriously think I'd be overweight in the first place?

If you ask people about weight-loss attempts, you get a lot of similar answers. Most people try a diet – a particular way of eating that's supposed to help you lose weight – and it works, almost regardless of what the particular diet is.

And then, of course, it doesn't. What happens? Life, usually. I asked my Twitter people to send me their stories, and I heard some of the many ways life derails diet: illness, pregnancy, bike crash, new baby, new job, menopause, bad work situation, even a church breakup.

Jill Dupleix's green cous cous with avocado tahini.
Jill Dupleix's green cous cous with avocado tahini. Photo: William Meppem

But sometimes, it's just that you get really tired of not eating bread. Or of tracking every meal. Or of eating things that are different from what your friends are eating.

The common thread running through the stories I've heard – not just this time, but in 20 years on this beat – is also what study after study has confirmed. People can lose weight until they can't. They go on a particular diet, and as long as they stick to it, they succeed, but they usually can't stick to it forever. "Regain happens when we decide to come back to our comfort zone," one tweeter told me.

Weight loss is, for most people, a toggle between diet and not-diet. Diet = weight loss, not-diet = weight gain. So why on God's green Earth are we spending all our time arguing about the difference between this diet and that diet, when people lose weight on all of them? The obvious, stare-you-in-the-face problem is the difference between diet and not-diet.


The difference is rules. Diets have rules. Eat this, not that. Eat now, not then. Eat this much, not that much. Eat this with that, but not with the other thing.

The rules insulate you from the come-hither, obesogenic, food environment known as normal. Instead of going out into the world of tasty, convenient food with a hazy idea of moderation, you go out with a plan. And it works.

What if normal had rules? What if, instead of "moderation," you had specific strategies to navigate normal? In 2017, researchers recruited 42 volunteers and put them on a "low-calorie powder diet" (appetising!) for eight weeks. Participants lost an average of 12 per cent of their body weight.

Where our weight is concerned, we've been the victim of learned helplessness.

This sounds like a setup for the same old story: They would all regain the weight, and then some, over the next couple of years. And some of them did gain; 20 regressed over the year they were tracked, although not quite back to their original weight. An additional 13 maintained their weight loss, give or take. But nine continued to lose.

What did they do that the regainers didn't? In this study, unlike most, the researchers conducted detailed interviews and included quotes from the participants. The results are striking. The weight losers made rules.

"Monday to Thursday I eat 1200 [calories or 5020 kilojoules], and Friday, Saturday, and Sunday I eat what I want but still reasonable."

Adam Liaw's roast chicken and vegetable salad.
Adam Liaw's roast chicken and vegetable salad. Photo: William Meppem

"I can buy the chocolate today, but I will not eat it until Saturday."

"Candy is a treat for me, and at weekends I reward myself for not eating it the rest of the week."

"I have a maximum limit of 2.5 [hours] between my meals."

"Each main meal must not contain more than 500 calories."

The regainers struggled.

"To resist a craving is like trying not to breath[e]. At a certain point you have to surrender."

"If I am tired or have had a hard day at work or have controlled my food for some time then I feel like I deserve it, then I eat crisps, and chocolate – sometimes several days in a row."

We've all been there! It's tough, struggling with the call of food. And diets fail because rules are hard to follow. So the key question is: How can you find the rules that you're most likely to be able to stick to?

Try every diet!

Diets are useful for the very obvious reason that they usually help you lose weight. So use them for what they're good for without expecting them to be a permanent solution. They are, instead, clues to a permanent solution.

Where our weight is concerned, we've been the victim of learned helplessness. We've been told – by experts – that weight loss is the province of experts. We need a list of rules developed by somebody else, often somebody with a complicated physiological explanation for why eating their particular way is better than eating all other ways. Enough already! Think about all those diets by all those experts as a smorgasbord of rules and strategies. Go down the line, mix and match.

In my own house, my own husband kicked off a weight-loss effort with a month of no-alcohol veganism. He knew he wasn't going to eat that way for the rest of his life, but he thought he was overindulging in butter, meat and wine. He found that doing without for a while reset his appetite for those things at a lower level. To keep it there, he switched to olive oil on his toast, black coffee and smaller meat portions. Eighteen months later, he was down 40 pounds, and he has stayed there. (He is, however, building a wine cellar; some rules just won't take.)

I have different rules:

  • Put off breakfast as long as is comfortable (I wait for the first hunger pang).
  • Don't eat more than 3350 kilojoules during the day; the rest at dinner.
  • Never eat after dinner; the kitchen is closed.
  • Other than a little chocolate, desserts only on special occasions.
  • Be vigilant at home and more relaxed at parties or in restaurants. (Remember those?)
  • Keep junk food and any food I find particularly tempting (yes, cashews) out of the house.
  • Always have fruits and vegetables on hand for snacks.
  • Weigh in every day.

When rules work, weight loss works. When they don't, it doesn't. A Twitter friend told me one simple rule worked for him: No eating in the car.

Try a diet knowing that there's nothing magic about it. They all work by restricting your intake to the point where you expend more calories than you take in. (Although it's possible that diets can affect the way your body burns calories, those differences are small; next month, I'll be writing about keto and its claims, so hold your fire.) But who's going to be better at figuring out a combination of rules that work for you – you, or some "expert" who has never met you?

Now that I've dissed experts, I will bring one into this conversation. Stanford University professor of medicine Christopher Gardner has done some of the field's most influential diet trials, and he, too, is frustrated by the arguments about the differences among diets.

"They agree more than they disagree," he told me over Zoom. "Limit added sugars and refined grains, and eat more non-starchy vegetables." Sure, people disagree about what comes after that – do you eat legumes? do you eat meat? – but "if you do those two things, you get 90 per cent of the benefits."

"You're biohacking," he said. "Try no snacking, try intermittent fasting, try including a little chocolate, try getting better sleep." Vegetarianism has worked for him, but he doesn't expect it to work for all of us.

And then there's that one thing that often gets overlooked: "You have to have joy and pleasure in food," Gardner said. If you enjoy what you eat, you have a much better chance of doing it forever. "It will be different from one person to the next, and there will never be a randomised trial of it."

There is absolutely nothing about weight loss that is true for everyone. For some, too many rules may feel like the road to disordered eating, and this is the wrong path. Others do find a specific diet that works for them long-term, and that's great. And some decide to try to eat healthfully, get some exercise and stop worrying about their weight, and that's great, too.

There are even some people who succeed with moderation. My hat's off to both of them.

Tamar Haspel writes a monthly commentary on divisive food-policy issues. She farms oysters on Cape Cod.

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