Why diets don’t work and what you can do about it

Diet is a vastly contested subject and it’s a multi million dollar industry worldwide. In the UK alone the diet industry is valued at around £2 billion. According to the latest NHS stats, the majority of adults in the UK are overweight or obese: 67% of men and 60% of women. It is estimated that as many as 1 in 3 people in the UK are on a diet most of the time. In women this could be as many as 67%. 

The diets

There are hundreds of diets out there from the carb free Atkins, to time restricted eating diets like the 5:2. The NHS has a useful review of the pros and cons of some of the more sensible diets here.

In truth, as pessimistic as it sounds, most diets don’t give us the results many of us are looking for. They are not leading to long term sustainable weight loss. Sadly it is predicted that up to 95% of people, who lose weight through dieting, will go on to regain it within 1 to 5 years. A good proportion will go on to gain even more weight.  

Bias in the science

Professor John P.A. Ioannidis talks about how there is bias in almost all scientific research on diet and nutrition. He has studied the literature in the area of nutrition and diet and concluded that the evidence pointing to most theories on diet and nutrition is extremely unreliable. It is subject to the biases of funders, scientists, sponsors and reviewers and there’s far too many variables at stake. It is therefore really difficult to point at firm conclusions as to which diets work and which ones don’t on a wide population level.

5 reasons why dieting doesn’t work in the long term: 

1. Willpower…

is a finite resource. It can be depleted in one situation and then is not available for the next. So relying on willpower alone when dieting won’t work. 

Say you successfully motivated yourself to go to the gym and workout after not really wanting to go in the first place. You were then really happy with yourself. When you get home there’s a big box of donuts on your kitchen table.

Will you have enough willpower left to resist eating one as a reward for your workout? Probably not, and that’s not your fault, it’s the way our brains are designed. 

Behavioural scientist Kelly McGonigal, in her book The Willpower Instinct, talks about willpower being like a physical muscle. You can exhaust your willpower muscle but you can also exercise it to get stronger. We have daily willpower reserves that get used up which is why we are much more likely to resort to eating unhealthy, high fat and sugary food after a long hard day at work. 

Failing at dieting is not about being weak willed or lazy, it’s an absolutely normal part of being a human being.

Kelly talks about ways you can train your willpower muscle. For example, purposefully placing a chocolate bar on the desk where you work and resisting the temptation to eat it for 20 minutes. Then once the 20 minutes is up take one small square and eat it and then put the chocolate bar away out of sight. I’ll talk about this in a later blogpost as it’s such a fascinating topic. 

Interestingly, willpower has shown to be much more effective when making decisions about eating healthy food rather than about depriving ourselves of certain food groups. 

2. Focusing on the short-term:

Most diets require drastic change far too quickly. Indeed, people will lose weight on diets in the short term, if they stick to them, but long term it is much harder. We see this miraculous weight loss results in celebrities and we all crave a piece of the action. 

However, for the vast majority of people these diets do not work sustainably as they rely on the individual continuing to put the effort in. This leads back to the problems discussed in point one above on willpower. Most people will end up putting the weight back on over time as they return to more “normal” eating habits. Hence the term yo yo dieting. 

Neuroscientist Sandra Aamodt in her TED talk “why dieting doesn’t usually work” refers to Dr Rudy Leibel’s work at Columbia University. He has found that people who have lost 10% of their body weight burn 250-400 fewer calories as a result of their suppressed metabolism. Meaning that to succeed as a dieter and keep the weight loss off you must continue to eat this much less food forever than someone of the same weight. 

3. We have not evolved to diet:

We can’t underestimate our evolutionary history here: our bodies were built to cling on to all available calories as food was scarce back in the hunter gatherer days. Our ancestors would look for high density calorie rich foods with as little effort as possible as they didn’t know when the next meal would come along. If the body is deprived of food it will naturally respond by slowing the metabolism and then making it harder to lose weight. This can result in unhealthy and potentially dangerous binge starve cycles. Our modern world doesn’t work so well in this context where any type of food is available 24 hours a day at the click of a button with minimum effort. 

This is why putting on weight is a lot easier than losing it. In his book Why We Get Fat And What To Do About it, Gary Taubes discusses how our modern diet is a relatively recent phenomenon and our bodies have not had time to evolve in response. We only began eating flour and “carbohydrates”, as we know them, 12,000 years ago and yet human beings have been on the planet for millions of years. We therefore haven’t genetically been able to cope as well with the relatively recent modern phenomenon of high carb, high sugar foods. Gary Taubes research is clear that if you want to lose weight sustainably then one of the best tactics is to limit carbohydrate consumption especially the highly processed types such as white flour, pasta, bread, crisps, sugar etc. This needs to be taken in context however, if you are training and exercising a lot your body does need carbohydrates.  

4. Our brain and the reward system:

Sandra Aamodt in her book Why Diets Make us Fat: the unintended consequences of our obsession with weight loss talks about how the brain has a crucial role here. The reward system in our brain is triggered when we eat tasty food. 

Our bodies have a finely turned energy balance system which keeps weight at a defined range based on a multitude of factors. It’s relatively easy for our bodies to go up and down within this range but very difficult to increase or decrease outside of this range (Sandra says it’s usually 12-15 pounds). This is controlled by the brain and she compares it to a thermostat. If you try to lose weight your brain responds by thinking the body is starving.

If this balance is disrupted research has shown that actually diets can cause more changes in the brain making this reward response even stronger and resulting in further cravings for sweet sugary food. That’s another reason why we are programmed to find weight gain much easier than weight loss. 

Have you ever tried the psychology experiment where you are told not to think about something – i.e. a white rabbit? Our brains automatically think of the thing we are told not to think of. It’s the same with depriving yourself of a food group or type of food. If you tell yourself you are not allowed any cake you might be able to stick to this in the short term. Eventually (assuming you are a cake fan) you’ll not be able to resist the temptation to eat the cake and the chances are you’ll have more than one small slice. 

5. We are all different and genetics play a huge role:

Another reason so many diets just don’t work is that we are all different. Our genetics, our physiology, our sleeping patterns, hormone balances, lifestyle, support networks, financial situations, behaviour patterns, cravings, digestion, work life, family life, mindset, attitude towards exercise and nutrition – the list goes on! 

So what may work for your best mate, in terms of losing weight, may not work for you and vice versa. 

Genetics play a huge component here. I know lots of people become increasingly frustrated when they try their hardest to stick to a diet and their partners end up eating whatever they like and losing more weight than them. Unfortunately some people are prone to put weight on more than others as a result of their genetic make-up. 

So what is the answer to successful weight loss? 

So what can you do if you want to lose weight sustainably and for the long term? No one wants to hear it but it’s going to take hard work, time, lots of self-reflection and learning, dedication, a few failures and reassessing the complex physiological, psychological and biochemical processes at play. 

In essence, there isn’t really one clear solution to fit all but there are healthy ways to approach the issue including: 

  • Focusing on eating nutritious and wholegrain foods rather than depriving ourselves of food groups: swapping white pasta, rice and bread for wholegrain is a good place to start. 
  • Allowing sufficient breaks between eating to enable insulin levels to drop (4-5 hours between meals and 12 hours overnight). See my previous post on this topic here. 
  • Focusing on portion control and size of meals and waiting 10 minutes after you finish your first portion before eating more
  • Cutting down on alcohol – there are lots of hidden calories in alcohol and it’s surprising how drinking can chip into the daily calorie allowance.
  • Getting better quality sleep (see my earlier post on sleep here for details)
  • Learning how to eat mindfully and intuitively and really listening to your body
  • Changing focus and learning to accept the body you are in whatever the size or shape
  • And of course getting lots of exercise and physical activity in! 

I’m building my coaching programme to help people work through the steps in finding a long term solution which works for them in terms of exercise, weight loss and nutrition. If you’d like some help in this area please do contact me as I’ve got coaching spaces available. 

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