Time for diet rethink
Why everything you know about weight gain could be wrong
Our old-fashioned understanding of obesity is slowly being challenged. Many scientists are realising that it is not the quantity of calories that are available in the food supply to a population that will affect obesity levels: it is the quality of the food available that causes obesity. Natural foods do not make populations fat. If a grain-, oil- and sugar-based diet is fed to any population of people, high levels of obesity occur.
Contrary to popular belief, our metabolism isn’t under our control and can vary dramatically depending on how much we eat. In those who diet a lot, their weight set-point – the level of energy (fat) storage that our brain calculates is necessary for our survival – shifts. The more diets you’ve been on, the higher your weight set-point and the slower your metabolism, because your body wants to protect you.
WHY (MOST) DIETS DON’T WORK Low-calorie diets
Very low-calorie diets (600–1,200kcal/day) like Lighterlife or Slimfast generally use mealreplacement shakes and soups and by definition are not sustainable if you want to have a good quality of life (ie be able to eat). Low-calorie diets cause changes in our metabolism. In the long run they raise your set-point, meaning that when you come off the diet you will regain all your lost weight and then some more until your new weight set-point is reached.
Low-carb diets
The Atkins, Paleo and Dukan diets are based on low-carb eating. Once carbohydrate intake is reduced to under 20 grams per day, a process called ketogenesis occurs. There are many celebrity advocates of ketogenic dieting, such as Kim Kardashian. It is an effective way of reducing weight but it has very unpleasant side effects, from a pounding headache to weakness, constipation and flu- like symptoms. The aim of the ketogenic diet is to starve your body of carbohydrates so it has to use up its own stores. By not taking in any food that can be broken down into glucose, you are forcing your body to start using the reserve that is stored in the liver. As with most diets, if you lost a lot of weight dieting this way, and then reverted to eating more normally again, you would regain all of that lost weight … and more.
Fasting diets
Popular examples of intermittent fasting are the 5:2 diet and the 16/8 diet. The 5:2 diet involves eating normally for five days, and limiting calorie intake to 500 or 600kcal for two days. The 16/8 diet advocates eating during an eight-hour window in the day. Both diets advise avoiding processed foods.
Unlike many other types of diets, intermittent fasting, just like low-carb dieting, remains popular – which means that it probably does work for some people. How does fasting work? By decreasing the opportunities for eating, and at the same time by avoiding processed foods, both the insulin profile and the omega ratio of the dieter will be improved and therefore the weight set-point will be reduced.
Vegetarian and vegan diets
Many vegans or vegetarians eat out of concern for the environment and animal welfare, but are these diets helpful for weight loss? Two of the main causes of an elevated set-point (and therefore weight gain) are unnaturally high insulin profiles and a relative deficiency of omega-3 compared to omega-6 essential fatty acids. Most vegetarians and vegans will eschew many types of processed foods because they contain animal products. This has a positive effect on both the amount of sugar and the amount of omega-6 oils they consume. However, frying foods in vegetable oils and consuming nuts and seeds (all high in omega-6) will have a detrimental effect on their omega profile, particularly as fish (a valuable source of omega-3) is excluded from their diet.
They also may consume a lot of bread, pasta and rice, which has a detrimental effect on their insulin profiles and weight. However, I find most vegans and vegetarians are aware of the quality of their food, are more inclined to prepare their own meals and more likely to avoid processed foods. If they can avoid taking in too much sugar or refined carbohydrates, their set-point (and weight) will fall.
WE NEED TO RETHINK OUR OMEGA FATS
Ideally, and throughout history, the ratio of omega-3 to omega-6 within our
bodies would have been between 1:1 and 1:4 (ie four times more omega-6 than omega-3). If we go back to hunter/gatherer times, when food was fresh and not based on grains or vegetable oils, we would see this range. People living in remote areas of the world today, who consume natural homegrown foods, will have these levels as well. But if you consume a Western diet, many omega-3s have been removed and large amounts of omega-6 have been added to foods that have been processed. So, the omega-3 to omega-6 ratio rises to a staggering 1:50 in some Westernised cities. The more omega-6 in the cell wall, the more that the appetite and weight regulating system will be ratcheted towards weight gain. An increase in the omega-6 to omega-3 ratio has been implicated in: Alzheimer’s disease, dementia, anxiety, mood disorders and suicide.
To optimise your omega-3 to omega-6 ratio, follow some simple rules. Eat lots of greens, and eat lots of meat and fish that have eaten greens – many farms feed their livestock an unnatural grain-based diet containing omega-6, in order to make them grow bigger faster (it works for animals as well as humans) so you will have to source grass-fed meat very carefully. This goes for fish, too – farmed salmon that has been fed grain will have a much poorer omega-3/omega-6 profile than line-caught fish. You can also include dairy products, including butter. Cut out vegetable oil, seeds (including grains) and processed foods.
WHAT ALCOHOL DOES TO YOUR WEIGHT SET-POINT
We know that alcohol can cause many serious illnesses, from heart disease and cancer, but how much does our alcohol consumption contribute to obesity? When we count the calories, it looks bleak. For UK adults, the average weekly alcoholic calorie intake is over 1,800kcal. But my book is all about not counting calories and instead questioning how different factors affect us metabolically. So, for now, let’s think about how it influences our weight set-point.
Interestingly, alcohol can improve insulin’s function, making it more efficient. But the side effect of this is when we drink alcohol it can lead to lower levels of blood sugar. The brain senses this and tells us to eat – producing the late-night craving for a kebab or morning fry-up. Alcohol, because of its effect on blood-sugar levels (and cortisol), heightens our appetite and makes us eat more. If this extra food is high in sugar, wheat or vegetable oils then it raises our weight set-point.
In addition, moderate or heavy drinkers have higher cortisol levels, causing fat to be distributed to the abdomen. By cutting down your alcohol intake significantly (or quitting), your weight set-point and weight will fall. If you are an occasional or light drinker, and if you make good food choices when drinking, then it is unlikely that it is having a significant effect on your weight set-point.
Extracted from Why We Eat (Too Much): The New Science of Appetite by Dr Andrew Jenkinson, published by Penguin Life at £16.99 © Dr Andrew Jenkinson 2019. Buy now for £14.99 at books. telegraph.co.uk or call 0844 871 1514