Month: October 2021

Does dieting make You Put on Weight

Why frequent dieting makes you put on weight – and what to do about it

Author

  1. Professor of Genetic Epidemiology, King’s College London

Disclosure statement

Tim Spector receives funding from several bodies including MRC, Wellcome Trust, EU and NIHR. He is co-founder of the British Gut project and Map My Gut Ltd. He advises Optibiotix Ltd. He is author of “The Diet Myth: the real science behind what we eat” – Orion 2016

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King’s College London provides funding as a member of The Conversation UK.

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Grapefruit diet? Probably not worth it. Sophie Jonasson from Sweden, CC BY-NC-SA

People who regularly go on diets tend to lose weight initially but bounce back and even gain weight after stopping the regime. This phenomenon – dubbed yo-yo dieting – is associated with changes in metabolism and is one reason why the vast majority of calorie-based diets fail. But exactly what causes these metabolic changes has remained a mystery – until now.

Previous studies in identical twins who differed in dieting patterns have shown that non-genetic factors are largely responsible. The working hypothesis was that when you gain weight you somehow “reset” your internal thermostat corresponding to the higher weight level and so when you lose weight – your body does all it can to return to that new higher set point. Now new research, published in Nature, explains why this happens to some people more than others and, importantly, how it could be reversed.

The study, by an Israeli group of scientists, mimicked human yo-yo dieters in lab mice. The researchers fed the mice in several cycles of alternating weight gaining and losing diets. They started with big, high-fat portions to fatten them up then slimmed them down with a diet of normal, light meals, then repeated the regime. Like humans, the mice slowly gained weight compared to other mice on steady diets of similar calories – even those on continuous high-fat diets.

Mice who bounced back and had increased weight regain after dieting had a lower energy expenditure than those on steady diets but still ate the same amount of food. We know this change in body metabolism occurs in yo-yo dieters. But the new study managed to figure out why – by looking at a forgotten organ of the body.

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In humans, this organ weighs nearly as much as the liver and is located in our lower intestines. It is the microbiome – the community of microbes that outnumber our cells and have a hundred-fold more genes and enzymes capable of digesting foodand regulating our metabolism and immune systems. It turns out that changes to the gut microbes were responsible.

Such hard work dieting, and no pay-off. cunaplus

There were marked differences in the gut microbes of the yo-yo dieting mice compared to the normal ones – including a reduction in diversity, which is correlated with obesity and other metabolic problems in humans. When they transplanted these disordered microbes from the weight regainers into normal mice on normal diets they saw them gain weight – showing that the altered microbes were ultimately responsible. They could explain how the microbes caused weight gain by looking at how they digested the plant fibre – their staple diet.

The study found that the altered microbes were under-producing healthy compounds generated from the plants called polyphenols (flavonoids) in the gut after dieting. These polyphenols are key to a healthy gut and the reason why many brightly-coloured foods are gut friendly. Taking poyphenols has in fact been associated with better health and less obesity. The exciting result of this is that, because microbes are involved, the changes post-diet are potentially reversible.

Avoiding the yo-yo trap

The researchers tried a number of methods to reduce the weight gain in the yo-yo dieting mice. First, they gave them antibiotics which altered the microbes and increased polyphenol levels. This cured the problem, but isn’t exactly a practical solution for humans. They then tried fecal transplants which also worked, but are again a bit drastic in humans. As taking a tablet is safer and easier, they then tried to replace some of these specific polyphenols by supplementation in the diet. Luckily, even this could reduce the weight gain.

So what are the lessons for humans? Assuming a similar mechanism is at work in humans, which is likely, it’s pretty clear. Episodic weight loss can be metabolically dangerous – damaging your microbes and making you burn less energy. The solution – while we await some magic supplements – is looking after your microbes as you transition back onto normal foods after a diet. In particular, you need to feed them plenty of fibre and polyphenol-rich foods which, as well as the obvious fruit and veg, include nuts, seeds, olive oil (extra virgin), coffee, dark chocolate and even a glass of red wine.

The best approach if you really want to lose weight long term is to avoid crash diets and calorie counting altogether, which are doomed to fail. Instead eat real diverse food, plenty of fibre and let your microbes take care of the rest.

More on evidence-based articles about diets:

Prevent Weight Gain

By Claire Madigan, Senior Research Associate and Henrietta Graham, PhD Researcher, Loughborough University

Loughborough, Oct 2 (The Conversation) Between the ages of 20 and 55, most adults gain between 0.5 and 1kg a year, which could see some people become overweight or obese over time. This weight gain isn’t usually the result of overeating large amounts of food.

Instead, it’s usually caused by eating a small amount – around 100-200 extra calories – more than is needed each day.

The good news is that we may be able to prevent ourselves from gaining weight by making small changes to our diet or physical activity. Our recent review found that eating 100-200 calories less, or burning an extra 100-200 calories each day, may be enough to stop ourselves from gaining weight in the long run.

This is known as a “small-changes approach”, which was first proposed in 2004 by James Hill, an American expert on obesity, to help people manage their weight.

Many small studies have investigated the use of the small-changes approach for weight management. We combined the results of these smaller studies into a larger review to get an average (and more statistically reliable) result of the effect of this approach on weight management. We looked at 19 trials – 15 of which tested a small-changes approach to prevent weight gain, and four that test this approach for weight loss.

We analysed the data of nearly 3,000 people in weight-gain prevention trials, and 372 people in weight-loss trials. Participants were aged between 18 and 60, 65 per cent of whom were female.

In those who used the small-changes approach to prevent weight gain, we found that participants gained almost 1kg less compared with those who didn’t use this approach over a period of eight to 14 months. The 1kg difference was statistically significant, meaning it was unlikely to be the result of chance.

While the small-changes approach was shown to be effective for preventing weight gain, it was not proven to be effective for weight loss.

The trials we looked at used a number of different small changes to help participants prevent weight gain. Here are some of the successful techniques used in these trials:

Get off the bus one stop earlier and walk the rest of the way. You may end up walking ten to 15 minutes more and this could help you burn up to 60 calories. Doing this on the way home as well could mean you burn up to 120 calories.

Skip the chips that come as a side. Small portions of oven chips served alongside main meals contain hundreds of calories . Saying no to these – or opting for a salad or vegetables as a side instead – could help you reduce your daily calorie intake by up to 200 calories.

Switch from a regular to a diet drink. Although it might not taste the same, making this switch could reduce your calorie intake by 145 calories. However, recent research suggests that switching to diet drinks may not be great for weight management – so choosing to drink water instead of your regular fizzy drink might be best.

Have an Americano instead of a latte. The milk in a regular latte can contain up to 186 calories, so switching to an Americano could prevent weight gain.

Add one less tablespoon of oil while cooking. One tablespoon of olive oil, for example, contains slightly over 100 calories, so using less can be one way of avoiding additional calories.

If you have something sweet, save half of it for tomorrow. Eating only half a KitKat, for example, could reduce your calorie intake by about 102 calories – and give you something to look forward to tomorrow.

Take one or two fewer potatoes in your roast dinner. One medium roast potato can contain as many as 200 calories, so be mindful of how many you put on your plate.

Take phone meetings while walking. You could burn an extra 100 calories if you opted to take a 30-minute phone call on the go.

Avoid sweets. Saying no to cakes, biscuits and other sweets could help you easily cut an extra 100-200 calories from your diet – maybe more, depending on the food.

Take your dog for an extra 30-minute brisk walk each day. The dog will appreciate it, and you could burn over 150 calories.

The small-changes approach has many advantages for managing weight. First, small changes are easier to incorporate into everyday life over larger ones. For example, it’s easier to eat 100-200 fewer calories a day than to eat 500 fewer calories each day (basically, an entire meal).

Small changes are also easier to maintain in the long run, which is key to managing weight. And, if people succeed at making these small changes, it may lead them to make bigger changes in their life. (The Conversation) RUP