Seven easy ways to beat the ‘fat gene’

Fat gene
Around one in 65,000 people in the UK have the faulty version of the BSN gene, also known as 'Bassoon'

When no amount of dieting or exercise seems to be shifting excess weight, you start to wonder if there’s something else at play. A new study seems to confirm that there is – at least for some of us. Around one in 65,000 people in the UK have the faulty version of the BSN gene, also known as ‘Bassoon’, with carriers six times more likely to be obese. The paper suggests that as we age, the faulty versions of the gene hamper its ability to transmit feelings of fullness to the brain, leading to a reduction in appetite control.

The study’s author is Giles Yeo, a professor of molecular neuroendocrinology at the Medical Research Council Metabolic Diseases Unit at the University of Cambridge. He says that having the mutation “severely increases your risk of ending up with obesity”, the equivalent to an additional four body mass index points, or 10 kilograms in weight. “It’s rare,” he says of the mutation. “But it’s shone a light onto a new gene never before linked to obesity.”

Currently, there is no test available to check whether you have the mutation and it’s too early to know how lifestyle changes may impact it. Not every carrier will be obese, according to Prof Yeo, as “10-15 per cent of people [with the mutation] will have a normal weight”.

But as in the case of other “fat genes” (such as MC4R which, when faulty, fails to accurately tell our brains how much fat is stored, or the FTO gene, which can lead to a genetic preference for high-fat foods), lifestyle tweaks may help to counterbalance the risk. For carriers of FTO, identified as the first obesity-related gene, “physical activity will mitigate against this genetic burden by 50 per cent”. As research into BSN continues, here’s how to tweak your diet to offset even the unluckiest genetic lottery.

Track what you eat – and then eat less of it

It’s become an unfashionable concept, “but the basic fact is that you can’t lose weight unless there’s a calorie deficit,” says Ian Marber, a nutrition therapist. For clients who insist they can’t drop excess weight, “I often suggest that they download, just for a short period of time, an app like My Fitness Pal, and then enter everything they eat honestly, [and] don’t kid themselves”. 2018 figures from the Office for National Statistics show that a third of UK adults underestimate their calorie intake.

Diet tracker
Tracking what you eat is a good way to monitor how many calories you actually consume - Getty

To lose around 1.5lbs a week, women should consume 1,500-1,600 calories each day (the NHS suggestion is 2,000), and 2,000-2,100 hundred daily for men (for whom the recommended amount is 2,500), though this should be adjusted for age and starting weight. Within that, “you need to make sure that you’ve got the right level of nutrition, because in truth, you could have a bottle of wine and a pack of Haribos… as long as it’s 1,599 calories, you’ll still lose weight.” A protein and fibre-rich diet high in legumes, fish and leafy greens will lead to sustainable weight loss – without the sugar crashes after things like booze and sweets – over the long-term.

Eat carbs – but offset them with protein

Marber “absolutely do[es] not demonise carbs”, but if the intake of foods like wholemeal bread or potatoes isn’t suitably balanced with protein, it can lead to higher levels of insulin resistance, commonly associated with conditions such as obesity, Type 2 diabetes and high blood pressure. “You need to offset the carbs with protein,” Marber says. “By having a little bit more protein in the diet, it can enable you to keep your glucose a little bit more balanced, which, in turn, will help you regulate your appetite.”

No foods need to be off the menu completely, Marber adds; rather, better portion size is the goal. And make sensible choices, like swapping a bowl of risotto for a piece of chicken or fish with one or two heaped tablespoons of brown rice, and vegetables.

Snack more often

Adding a mid-morning and mid-afternoon snack to your diet doesn’t need to tip your calorie count over the edge, Marber says. Pairing complex carbohydrates (such as oatcakes) with protein (like chicken) “reduces appetite, and secondly, it encourages or at least allows the fat cells to give up some of their fat to be turned back into energy.” It does this by slowing the digestion of carbs and delaying their absorption into the blood, which helps to maintain more stable glucose levels and reduces the likelihood of their being stored as fat. Still, keep the components healthy. His go-to snacks include mashed-up fish with cherry tomatoes and pumpkin seeds, or “a pear and a couple of brazil nuts”.

Drink less alcohol

Boozing makes us hungry. The practice of drinking an apéritif to trigger hunger at the beginning of a meal dates back to at least the 5th century AD, while a 2017 paper published in Nature concluded that alcohol-induced overeating is a “biological phenomenon occurring across mammals.” Inhibitions leaving you after a few drinks may also have a negative impact on sticking to a healthy regime. “You care less after half a bottle of wine,” Marber says.

Alcohol also increases your weight. At around 120 calories for a small glass of wine, a few drinks with dinner can easily add up. “And there is some research to suggest that alcohol will actually slow down the way that fat cells release their fat,” says Marber. A study from the University of Lausanne  concluded that drinking “probably favours lipid storage and weight gain”.

Choose vegetable fats over animal fats

“There does seem to be consensus that vegetable fats are healthier in general than animal fats,” says Mark Bittman, the author of more than 30 books on food including Animal, Vegetable, Junk. Such was the case in a Harvard study of dietary data from more than 90,000 people, which found that higher consumption of unsaturated plant-based fats was linked to a 16 per cent lower risk of dying from any cause, while higher intake of animal fats saw a 21 per cent rise in death from any cause.

Bittman has himself experienced the benefits of choosing unsaturated vegetable fats (such as avocados, olives and nuts) first-hand. At 57, with pre-diabetes, high cholesterol and carrying an extra three stone, he began a VB6, or the vegan before 6pm diet, which significantly reduced his consumption of animal fats (such as full-fat dairy, eggs and meat). After losing the weight (and associated ailments), close to two decades later, he still suggests taking two thirds of your calories from unprocessed fruit and vegetable sources to maintain body size and healthy blood levels.

Cut down on stress

Elevated levels of cortisol (the stress hormone) in the blood make it “more likely you’re going to have fat cells accumulating around the middle,” says Marber. Worse still, that weight gain may make you more stressed, further perpetuating the cycle. Dieting is a short-term solution, he says, but unless you deal with the root causes of that stress, lasting change is unlikely.

Sleep – or not getting enough of it – can also be a major driver of both stress and weight gain. Extensive research has shown that poor sleep activates the stress system, stops the body burning fat, promotes higher levels of ghrelin (the hunger hormone), and decreased levels of leptin, which tells our brains how full we are. Poor sleep also makes us less likely to adhere to healthy eating patterns, according to numerous studies (such as a 2020 paper from Uppsala University), raising the likelihood of overeating and weight gain. So get your sleep habits in order.

Get a fibre boost from single-ingredient foods

As a nation, we’re fibre-deficient. The average person consumes around a third less than the recommended 30g per day, notes Marber. A 2019 paper found that “the most influential predictor” of weight loss for overweight or obese adults on a calorie-controlled diet was high levels of fibre, which its authors said “promotes weight loss and dietary adherence”. Part of our deviation from fibre is down to an over-reliance on ultra-processed foods, such as sliced bread, cereal, sauces and yoghurts (as well as biscuits, cake and pizza), which now account for more than half of what we eat in Britain.

Eat plenty of legumes, says Marber. Go for chickpeas and lentils, nuts (though “one has to be mindful of the calories”), dark green leafy vegetables and “hearty fruits; anything with a thick skin, like apples and pears. Even a baked potato is good, as long as you eat the skin”.


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