Here’s why your diets keep failing

Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.

For decades you have been told that it’s all your fault; that the reason you don’t succeed on your weight loss journey is due to a lack of willpower. 

But, there’s a bigger problem why you keep failing on each weight loss attempt and it’s certainly not due to a lack of willpower. It’s due to a very clever part of the brain called the hypothalamus preventing you from doing so. In fact, there are several well-researched biological pathways that protect our body from weight loss and ensure our weight rebounds each and every time. Research shows that in order to lose weight and make it stick, you must eat well and exercise for a month - then have a month off. 

Even since overweight and obesity became a problem – the 1980s – we have being brainwashed to believe that the answer is in continuously cutting the calories, largely driven by a multi-billion dollar dieting industry. Traditionally, any sort of weight loss program promotes a continuous caloric restriction to induce a continuous weight loss. However, a weight loss plateau tends to kick in around three to six months and a person will start to regain the lost weight. Consequently, 95% of people fail on their attempts to lose weight. Not because of a lack of willpower, but because of the biological protections left over from our time on earth as hunter gatherers. 

When a stress is imposed on the body, it starts to work differently - to defend its level of fatness and go back to its starting point – otherwise known as our ‘set point’. It’s not possible to lose weight without your body fighting it. After all, this is evolution!

The key to sustainable weight loss lies in these 3 simple tips:

1. Eat more not less

95% of the population fail to meet basic nutrient requirements; they fall well below the 2 serves of fruit and 5 serves of vegetables each day. The modern-day environment means we are reaching for far too many processed foods and wrong information has led to a fear of certain foods – for example, carbs, fruit and dairy. Consequently, many of us are actually deficient in various vitamins and minerals, despite our enormous calorie intake. 

One of the key components of a successful weight loss journey lies in increasing your food intake from wholesome, nutritious foods. You certainly shouldn’t be cutting anything out of your diet. We can all cut certain foods for a period of time – typically one to three months – but cravings for high fat and high sugar foods will come back with vengeance. Research utilising brain imaging has confirmed this: there is a heightened activity of the limbic (reward) system in the brain following weight loss, which drives an increased desire for those foods which had been cut from the diet. 

2. Impose ‘diet breaks’ on your weight loss journey

That clever part of the brain – the hypothalamus – that works to regulate our weight day-to-day; well it’s great news for people trying to maintain their weight, but this area of the brain works against us when we try and shed the kilos. This is the result of human evolution! What once was beneficial during a time when food was scarce – our hunter-gatherers time - is no longer needed; our evolutionary propensity for weight gain dominates over sustained loss.

Diets advocate restrictions and are founded on the idea that you just need willpower to lose the weight. We all know that a large weight change is possible through dietary restriction. But, eventually, the weight will come creeping back. There are at several well-researched biological pathways - for example, drop in metabolism, change in substrate utilisation, change in appetite hormone signalling - that kick into place when a stress is imposed on the body. 

The answer to sustainable long-term weight loss does not lie in repeatedly dieting or restrictive eating; the two indicators that actually accelerate fatness rather than reversing it. The only way to prevent these biological protections kicking into place is to impose ‘diet breaks’ along the way – specifically, every 2nd month - a month on, month off plan.

3. Find the enjoyment in activity

70% of our population don’t even move; they fail to meet the measly guideline of 30 minutes of exercise on 5 days per week. Chronic inactivity is physiologically abnormal and the human body fails to function properly to maintain health with insufficient amounts – historically ‘normal’ amounts – of physical activity.

Stop the all-or-nothing mentality and take up something you enjoy. Just don’t do the same exercise or work at the same intensity every day – mix up what you do. Exercise plays a vital role on your weight loss journey, to minimise the amount of weight you lose from muscle stores. It also plays a vital role in weight maintenance as research has proven it as a key predictor of keeping the weight off.  

Next time you decide to embark on a weight loss journey, reflect for a moment; if you always do what you’ve always done, you’ll always get what you’ve always got. Make the change that’s necessary to shift that weight for good.

About Dr Nick Fuller

Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.