Why you can’t keep off the weight you lose

You’ve lost 10lb and you’re feeling good. Your clothes fit better. You look trimmer. But more importantly, you know you have done your health a massive favour.

“Over a quarter of our population is obese, two thirds of us are overweight or obese, and many illnesses are linked to weight,” says Dr Harvinder Chahal, a consultant in endocrinology, diabetes and bariatric medicine at Imperial College NHS Trust. Dr Chahal says that for the majority of people in the UK, losing just 10 per cent of their body weight can significantly reduce the risk of diseases including cancer, heart disease, type 2 diabetes and osteoarthritis.

So why, after losing weight do many of us find it creeping back on again? If this sounds like you, you’re not alone. Three years after participants in one study ended their weight-loss programme, only 12 per cent of the 204 participants had kept off at least 75 per cent of the weight they’d lost. In fact, 40 per cent had gained more than they had originally shed. 

However, yo-yo dieting is not only dangerous for your physical health, it can be debilitating to your sense of self-worth. “There still seems to be a stigma attached to weight,” says Dr Chahal. “The assumption is that patients who cannot keep the weight off are just eating too much and not exercising enough.” In fact, it may not be as simple as that and your willpower may not be the problem.

Dr Chahal says there are myriad factors to consider, such as “environmental, genetic and even changes in gut hormones”. So, what exactly is stopping you from keeping off that weight?

Why can’t I keep the weight off? 

Weight loss can lead to a decline in your resting metabolic rate, or how many calories you burn while resting, Dr Chahal says. In 2016, American researchers published the results of a six-year long study following the former contestants on a weight-loss reality television show, The Biggest Loser. 

During the show, contestants lost an average of 125 pounds each. Six years later, however, researchers found that their resting metabolic rate was far slower than it had been before taking part in the show, meaning that they were burning fewer calories when in a state of rest and would have to work harder (and cut back on more calories) to keep the weight off. The result? They had regained much of the weight lost during the show.

We do not know exactly what mechanism causes weight loss to slow metabolic rate, says Dr Chahal, but the more weight you lose, the more likely your basal metabolic rate will adapt and reduce. Rapid, extreme weight loss makes it even more likely. 

Other changes can also get in the way of maintaining your weight loss. Hormones, for one. Ghrelin, the hunger hormone, will start to increase as you lose weight while leptin, a protein hormone signalling when you are full, will drop. This means you will want to eat. 

“There is also research suggesting that your genes can be involved in weight management as well,” says Dr Chahal. This set point theory states that our genetics, as well as environmental factors and early years experiences, help to establish your body’s weight set point- an innate weight range that your body tries to maintain. Once you fall below this set point, the hormonal and metabolic changes above kick in, explains Chahal. “It’s the body saying: ‘look, I’ve been at this weight for a very long time and now you’ve brought me down to lower weight. I want to try to get back to the original weight.’”

The psychology of yo-yo dieting

Biology aside, there may be psychological factors influencing your weight regain, suggests Dr Chahal. “Sometimes there are psychological triggers to weight gain. If the triggers return, the weight returns with them.” If you tend to reach for junk food when stressed, then a new deadline or looming redundancies at work can push against your weight loss.

Even if your healthy habits are not tied to your mental health, restrictive diets can wear down your resolve and self-control over time. The popular Keto diet – which is high-fat, medium-protein and low-carb – is a good example, says Dr Chahal, because not all calories are created equal. “Fifty kilocalories of carbohydrates in brown bread, for example, will create a different insulin response to, let’s say, 50 kilocalories of protein.”

Calorie for calorie, carbohydrates create a bigger spike in insulin (the hormone that regulates your metabolism). More insulin means your body burns less fat. “This is why the Keto diet became so popular,” says Dr Chahal. But sustaining a no-carbs regime over a long period can be difficult, he explains. Soon enough, real-world routines reassert themselves and carbs re-enter your life.

“It’s not at all surprising that we regain weight. It’s how we’re built,” explains Prof Peter Rogers, a psychologist at the University of Bristol, whose research focuses on human appetite and weight control. “As mammals, we’ve evolved the capacity to store excess energy as body fat. That hedges against the time when it isn’t readily available.” For the privileged in today’s world, however: “Food is all around us. So we have to develop and exert countermeasures.”

Dieting and weight loss has two phases, Prof Rogers explains. At first, you need to significantly reduce the calories you consume, so that your weight drops. Once you find yourself at a healthy weight, you can increase your calorie intake a little. Raise it too much, however, and your weight will creep up again, so you still need to be mindful. This second stage is often the hardest, he suggests, because it is easier to do something dramatic, and with obvious gains for a month, than to do something sensible forever, with no motivating weight loss. This makes it easy to fall into a pattern of losing and regaining weight.  

Why yo-yo dieting harms your heart 

Yo-yo dieting is not only dispiriting, but has been linked to an increased risk of heart disease in women, says Dr Neil Srinivasan, a consultant cardiologist and heart rhythm specialist. “Similar results have been reported in men and this may be due to a reduction in lean muscle during weight loss, which is replaced by fat when weight is regained,” he explains. “This overshoot in fat gain increases the risk of high blood pressure, high cholesterol and diabetes which are associated with cardiovascular risk.”

The bigger the bounce in the yo-yos, the greater the risk. “The more weight lost and regained during yo-yo dieting, the greater the risk,” Dr Srinivasan says.  A study of 9,509 adults found that the risk of a coronary event was 64 per cent higher among patients with the highest variations in body weight than it was among those with the lowest variations. The risk of a cardiovascular event was 85 per cent higher, death 124 per cent higher, myocardial infarction (heart attacks) 117 per cent higher, and stroke 136 per cent higher.

What’s the best way to keep weight off?

In 2009, researchers randomly assigned 811 overweight adults to one of four diets: low fat, high fat, average protein and high protein. At six months, all the participants had lost an average of 6kg (7 per cent of their initial weight). After 12 months, however, all began to regain weight. Another study, comparing fast and slow weight-loss programmes, found that after three years, 76 per cent of all participants had regained their lost weight, whichever method they had adopted. Even those prescribed to take weight-loss drugs will begin regaining weight if they come off their medication, explains Dr Chahal.

“As a general principle: lower carbs, more protein, more vegetables,” says Dr Chahal. Fibre may be the key here, partly because it keeps you feeling fuller for longer. A 2015 study suggested that simply eating 30g of fibre a day can help you lose weight, lower your blood pressure, and improve your body’s response to insulin just as effectively as more prescriptive diets.

“But I don’t think there’s one diet that fits everyone,” Dr Chahal says. “Everyone responds to dietary measures in individual ways. If the question is: what’s the best diet for long-term weight management? The answer has to be: whatever strategy is sustainable for you.” 

Exercise is also crucial. While the rate at which we burn food slows by around 15 per cent with each diet we attempt, exercise can help restore our metabolism. In 2004, realising that the epidemic of obesity in the United States was adversely affecting recruitment into the military services, the US Army Medical Research and Development Command commissioned a review of scientific evidence on body weight.

“One of the best predictors of success in the long-term management of overweight and obesity is the ability to develop and sustain an exercise programme,” it concluded. But, “for many individuals, changing activity levels is perceived as more unpleasant than changing dietary habits.” Reviewing the scientific literature, they found evidence that home exercise equipment (a treadmill, for example) increased the likelihood of regular exercise and was associated with greater long-term weight loss. Strength or resistance exercise combined with aerobic activity had the best long-term impact on weight-maintenance, but participants picking the form of exercise that they liked – or hated the least – was vital. 

How to lose weight after 40

“Perimenopause can last for several years, even a decade, and during this time many women find that their metabolism changes and they are more likely to put on weight, especially in the middle,” says Dr Louise Newson, a GP and menopause specialist.

This abdominal fat produces inflammatory chemicals in the body which, alongside other metabolic changes, including increased risk of insulin resistance, can actually increase risk of type 2 diabetes and cardiovascular diseases.

“During the perimenopause and menopause, our bodies try to combat falling oestrogen levels by obtaining it elsewhere, including a different form of the hormone produced by fat cells,” she says. “You might find yourself experiencing sudden and strong cravings for sugary foods and unhealthy fats – a desire that makes losing weight and maintaining weight loss tricky.”

But it’s not impossible. “An anti-inflammatory, Mediterranean-style diet is more likely to mean you will have improved energy, less likelihood of low mood, and can even reduce aches and pains,” says Dr Newson. HRT can also be useful, partly because it sparks metabolic changes.

Men might also struggle to maintain weight loss in later life as their bodies change, says Dr Chahal. “As we age, things are working against us, we may have other illnesses and our mobility might have reduced.”

Even those who stay active will start to lose muscle mass from their thirties onwards, research suggests. Less muscle means a slower metabolism and thus greater effort to burn calories. Eating more protein (ideally, 1.6g per kilogram of body weight per day) in conjunction with weight training, may be the best way to tackle that, according to the findings of a review published in the British Journal of Sports Medicine.