A new book exploring the science of appetite warns of the dangers of dieting and explains an alternative, healthier way to keep the body fit.
A compelling look at the science of appetite and metabolism, Why We Eat (Too Much), by Dr Andrew Jenkinson explores how the habit of repeatedly dieting tampers with the body’s natural appetite and satiety hormones, ultimately making it harder to control our weight. As a consultant gastrointestinal surgeon who performs gastric bypass surgeries at University College Hospital, Jenkinson’s office is the end of the line for morbidly obese clients. What he has seen in his clinic has convinced him that the standard model for weight loss and maintenance – energy in, energy out – does not stack up.
“Time and again I hear the same thing: I can lose weight, but I can’t keep it off,” says Jenkinson. “I’m seeing one client at the moment who is exercising five times a week with a calorie intake of 1,200 a day, simply to maintain her weight. Most doctors would say ‘you must be sneaking food’, because there’s not really a widespread understanding that our metabolism can shrink down significantly.” But it can.
Your Set-Point Is King
As a species the human race is getting fatter, that much is undeniable. The average man is six kilos heavier than 30 years ago, and eats on average 500 more calories each day. However, according to the calorie model we should be ballooning even faster than we already are. “We should be gaining four stone a year on average,” says Jenkinson.
The reason we aren’t is due to the clever balancing act performed by our metabolism. “Our basal metabolic rate [the number of calories we burn at rest] can change by as much as 700 calories a day, depending on whether we’re overeating or undereating, to keep us at our individual weight set-point,” explains Jenkinson. Each person’s weight set-point is determined by genetics, but external factors are also at play. “Firstly, the quality of the food. Secondly, stress factors in the environment,” he says.
After we stop dieting the metabolism will stay sluggish, so that when you return to eating in an unrestricted way, not only will hunger hormones (which have been shown to increase by 24 per cent after a six-month period of dieting) work hard to return you to your set-point, they’ll also tuck a little extra away in case there is another ‘famine’ looming. You have, in fact, reset your set-point, but not in the direction you might hope. “This is why diets work in the short term, but in the long term they are counterproductive,” says Jenkinson.
It’s not just dieting that can edge your weight set-point up. Stress will do that to you, too. “The stress hormone cortisol is an anabolic steroid,” explains Jenkinson. “If I treat someone with steroids, for example for an autoimmune disease, they will gain weight. Being stressed is the equivalent of taking steroids.” Jenkinson notes that those whose weight issues began in adult life had frequently experienced a significant life event, like starting a demanding new job, at the same time.
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The Westernised Diet
The third element of this perfect storm is our unhealthy Western diet. “It is hedonic and addictive with lots of vegetable oils and sugar, which mimic the effect of opioid drugs,” says Jenkinson. Bread, processed within an inch of its life, is one example of a highly addictive food we eat regularly: “High sugar and refined carbohydrate diets lead to higher insulin levels (the hormone that controls sugar), which leads to a higher weight set-point,” he warns.
Less widely recognised, but just as damaging, is the abundance of omega 6 fatty acids in our diets, which can wreak inflammatory havoc. Ideally, and throughout our history, the ratio of omega 3 to omega 6 within our bodies would have been between 1:1 and 1:4 (i.e. four times more omega 6 than omega 3). However, the ratio in some Westernised diets nowadays is a staggering 1:50, which can be put down to the fact that omega 3s are routinely removed from processed foods, while omega 6s are added to extend products’ shelf life. “This causes inflammation throughout the body, affecting the hypothalamus, or our weight control centre,” says Jenkinson. “In those who are obese, the hormone signals don’t get through, which means famine is always perceived, even in times of excess.”
Fortunately, this can be reversed by changing the quality of our food. A daily omega 3 supplement alone won’t fix the imbalance, but refraining from eating processed food can; although be aware that seemingly innocent nuts and seeds (including all grains), grain-fed chicken and beef are all also high in omega 6.
Jenkinson’s hope is that we will follow his advice instead of looking to “quick-fix” diets. “The diet industry wouldn’t be there without the obesity crisis, and the obesity crisis wouldn’t be there without the change in the quality of food available to people. If we could stop worrying about calories incessantly, get our omega 6 ratio down and reduce sugar by eating healthier foods, we’d settle at a much healthier weight without dieting.”
How to reset your weight set-point
“The whole crux of the book is that you can alter your weight set-point downwards, by altering the quality of the food you eat and reducing your stress levels,” says Jenkinson. Here are his tips:
- Eat food that’s as close to its natural state as possible: “If you can buy it in a greengrocer, butcher or fishmonger, that’s best,” says Jenkinson
- Prepare food at home, rather than buying ready-made meals or sauces, which are likely to contain vegetable oils.
- Reduce your insulin by cutting out sugar and refined carbs, like white bread, pasta, alcohol and white rice.
- Cut out polyunsaturated vegetable oils like sunflower, canola and rapeseed oils. Cook with butter, ghee, olive oil, or coconut oil instead.
- Choose meat and fish with higher omega 3 levels: grass-fed beef (check the label carefully), lamb (usually 100 per cent grass-fed), line-caught fish, or canned fish (in brine, not oil).
- If you are still struggling to lose weight, cut your carbs to 100 grams a day (most of us eat 300g a day).
- Do exercise that makes you sweat at least three times a week for 20-30 minutes.
- Get eight hours of sleep a night. Studies show that sleep deprivation can lead to consuming 300 calories extra per day.