Yo-yo dieting has traditionally been seen as something potentially dangerous – but new analysis suggests otherwise. Photo / 123RF
New research suggests that even if you regain some lost weight, you’ll still cut your risk of heart disease and diabetes.
You’ve tried the 5:2, cutting out carbs, giving up alcohol for a month. They work for a bit, then – dismayingly – all those lost pounds pile right back on as soon as you stop. The wasted effort and failure of willpower is disappointing, but there’s also the concern that “yo-yo” dieting – repeatedly losing then regaining weight – has traditionally been seen as something potentially dangerous.
Reported risks include increased risks of diabetes and heart disease, not to mention the replacement of firm muscle with wobbly fat. Hapless dieters are warned that if they put their weight back on, they may end up fatter and less healthy than before they began. How dispiriting.
According to the Health Survey for England 2021, 72 per cent of 16 to 24-year-olds are a healthy weight and only 8 per cent are obese. But by the time we are aged between 65 and 74, only 27 per cent of us can still boast a healthy BMI. Of the rest, 42 per cent are overweight and a staggering 32 per cent obese. It’s enough to send anyone diving into the biscuit tin.
But now a new analysis has found that people who lost weight – despite the lost pounds creeping back on – saw benefits to their health for at least five years.
Researchers at Oxford University looked at 124 trials involving around 50,000 people trying to lose weight. Around half of the dieters took part in behavioural weight loss programmes which supported lifestyle changes such as eating healthier food and doing more exercise. The rest decided to go it alone.
At the start, they had an average age of 51 and a BMI of 33, which is considered obese. They lost an average of between 2-5kg and typically regained at a rate of less than a pound a year.
Prof Susan Jebb is a public health nutrition scientist at the University of Oxford, and a co-author of the study. “Many doctors and patients recognise that weight loss is often followed by weight regain, and they fear that this renders an attempt to lose weight pointless,” she says. “This concept has become a barrier to offering support to people to lose weight.”
It’s true that studies show that regaining weight after dieting is the norm rather than the exception. In a 2018 analysis of 29 long-term weight loss studies, more than half of the lost weight was regained within two years, and by five years more than 80 per cent of the painstakingly shed pounds had piled back on.
But as this new study shows, that doesn’t mean that dieting was futile. While you might not fit into your trousers anymore, instead of causing metabolic carnage or triggering eating disorders, even “failed” weight loss seemed to leave people healthier.
“In our study, weight regain, on average, took at least five years, and sometimes up to 14 years to regain,” says Jebb. During the time your weight is lower, your blood pressure, blood glucose and cholesterol levels are lower. These are all risk factors for heart disease, so it’s very probable that your long-term risk of diabetes and heart disease is lower too.
“We can’t be absolutely certain because few studies have followed people up long term, but putting information from all the studies together, the trend is very clearly towards fewer cases of diabetes and heart disease among people in the group offered a weight-loss programme.”
In short, this study adds to evidence showing that being lighter – even for short periods – seems to improve longer term health.
Jebb points out that the study didn’t look at yo-yo dieting per se but, she says, “we found no evidence of harm to physical or mental health during or after a period of weight loss and regain”.
But doesn’t yo-yo dieting make us flabby by reducing our muscle mass and replacing it with fat – something that might slow our metabolisms further?
A study published in the journal Nature in 2020 suggested that while this might be true of slim people who repeatedly diet to become even skinnier, it may not apply to people who are overweight.
It stated, “Studies in which individuals with obesity were subjected to one cycle or three successive cycles of dieting failed to show altered body composition.”
And according to Johns Hopkins School of Medicine in the US, yo-yo dieting will not make it harder to lose weight in future.
“Most studies show that weight cycling does not affect the rate at which the body burns fuel,” it states. Also, a previous weight cycle does not influence the ability to lose weight again, or increase the amount of fat tissue or increase fat distribution around the stomach.
And in 2019 a mouse study found that mice subjected to several rounds of yo-yo dieting lived as long as mice kept at a stable weight on a low-calorie diet and much longer than steadily obese mice.
Jebb’s Oxford study also found that people who’d taken part in a weight-loss programme such as ZOE or Noom maintained health benefits longer than dieters who went it alone.
This might be because people who’d had behavioural support stuck with lifestyle changes such as eating healthier foods and being more active. In the longer term, these boosted their health even if they increased their calorie intake.
Diabetes researcher and GP Simon Tobin believes this could be an explanation. In January, Tobin co-authored a study showing that half of people with type 2 diabetes could put their disease into remission with the help of a low-carbohydrate diet.
He points out that some patients lost just 1kg of weight (around 2lbs) or less on the diet “but still managed to put their type 2 diabetes into remission. That shouts out to me that it cannot be weight loss alone that has achieved this.”
On the other hand, relying on new weight loss medications such as Ozempic or Wegovy without lifestyle support may leave people particularly vulnerable to yo-yoing.
Jebb says, “There is some preliminary evidence from individual studies that weight regain after weight-loss medication is stopped may be faster than after diet and exercise programmes.”
One of Tobin’s co-authors, Roy Taylor, is a professor of medicine and metabolism at Newcastle University and was awarded an MBE in the New Year’s Honours list for his work on diabetes.
This includes a study showing that an 800-calorie-a-day liquid diet can reverse the disease in many patients. Taylor says that half of the successful study participants needed to tackle weight regain.
In his book Life Without Diabetes, Taylor tells people “If your weight rises by 3kg above target, take immediate action. Either to go back to the liquid formula diet for a few weeks or drastically decrease your daily amount of food. Whatever you do, don’t abandon your hard work in regaining health. Make sure it is only a temporary blip.”
Jebb says, “Some people have a biological vulnerability to weight gain and we are surrounded by energy-dense foods and cheap deals. Obesity is a chronic relapsing condition, and it may be necessary for people to follow a weight-loss programme every few years to keep their weight down and manage their risk factors. It’s not an ideal solution, but until we have a better option, we should celebrate and support people who make repeated efforts to manage their weight to improve their health.”
The bad news: weight loss is hard. The good news: losing even a few pounds (or less!) can have huge benefits for your health.
Lose up to 5 per cent of your weight
Even losing a few pounds could reduce your risk of cardiovascular disease. Overweight and obese women who lost weight over two years decreased their total cholesterol scores, “regardless of the amount of weight lost”, according to a 2013 study in the Journal of the American Heart Association.
Lose 5 per cent of your weight or more
This is enough to lower your blood pressure and improve insulin sensitivity. Research shows people who lost 5-7 per cent of their body weight and added 150 minutes of exercise per week cut their risk of developing type 2 diabetes by up to 58 per cent or a staggering 71 per cent for people over 60 years old.
Lose 10 per cent of your weight
By some markers, “overweight” means being 10 per cent over your body’s ideal weight range, and “obese” is 20 per cent and higher. So, for a 150lb person (68kg), losing 10lbs (4.5kg) can place them in a whole new medical bracket. A 10lb weight loss can also decrease progression of knee osteoarthritis by half.
Lose 15kg
Losing an impressive 15kg is enough for most people to put their type 2 diabetes into remission by stripping fat from the pancreas and liver. High levels of fat in the liver increase the risk of health problems, such as diabetes, high blood pressure and kidney disease.
People with diabetes who lost this amount over eight weeks saw liver fat fall by 30 per cent and both liver insulin sensitivity and fasting blood sugars return to normal.
Kate Tynan, 44, lives in Marple in Greater Manchester with her husband and two children. She runs Little Button Bakery which specialises in modern, creative wedding cakes.
In December 2021 I was 12st 3lbs (77.5kg), which was too heavy for my 5′6″ frame. I started weight training at a local gym, Transformation HQ, and followed a diet plan from my trainer.
Less than a year later, I was just 9st 11lbs (62kg). This felt a little too thin, so I let myself go up to around 10st 4lbs (65kg), which makes me a size 10 to 12.
However, if my weight goes over 10 st 6lbs (66kg), which it has a couple of times, I reduce my calories to 1,500 a day and up my protein to 40 per cent of my diet for around three weeks. I also increase my gym sessions from three times a week to four or five which is key to keeping my weight under control. I aim to lose 1-2lbs (0.45kg - 0.9kg) a week.
I think it’s unrealistic to assume lost weight will never creep back on, especially if you work as a baker. Sticking to a super strict diet forever just isn’t feasible for most people. I think it’s healthy to do these mini-diets regularly. This way you can enjoy some less healthy food but not totally fall off the wagon.
It’s reassuring to see evidence “yo-yo dieting” isn’t going to harm me and that by keeping my weight down, I’m benefitting my long-term health.
The new doco follows the Sussexes' Harry & Meghan, Live to Lead, and Heart of Invictus.