Diets don’t work. They only set you up for failure in the long run, say a growing number of experts backed by research.
As long ago as 1992, a National Institute of Health Panel in the US reviewed weight-loss studies and found that 95% of people who lost weight through dieting regained it all within five years.
Subsequent studies have had similar results, with a 2007 University of California review arriving at an even more startling conclusion. It found that 66% of dieters regained even more weight than they initially lost.
The HSE clinical lead for obesity Prof Donal O’Shea believes diets are counterproductive. “Severely restricting the amount you eat may cause changes to your body that lead to weight regain over time. Calorie-restricted diets lead to short-term weight loss, but regain normally occurs after 12 months.”
All of this is proof that dieting doesn’t work, says Ciara Flood, a registered dietitian and certified intuitive eating counsellor. “If weight loss achieved in the short term is not maintained in the long term, then dieting is not sustainable,” she says. “People don’t fail at dieting. Dieting fails people.”
Traci Mann, a professor of psychology at the University of Minnesota and author of Secrets from the Eating Lab: The Science of Weight Loss, the Myth of Willpower, and Why You Should Never Diet Again, agrees: “If the vast majority of people regain weight after a diet, this isn’t the fault of the dieter, but of dieting,” she says.
Yet both understand why we continue to believe in the transformative potential of dieting. “Our culture sells the message that to be thinner is to be more attractive and that we should continually strive to lose weight if we want to feel good,” says Flood.
“We’re also told that to be in a larger body is to be unhealthy and that good health can only be achieved through weight loss. These are powerful messages but neither of them is true.”
The truth is that our bodies don’t want us to diet and when we try, they work against us to maintain our weight. “That’s because our bodies perceive sudden calorie restriction as a threat to survival,” says Dr Annemarie Bennett, assistant professor in dietetics at Trinity College Dublin.
“When we lose weight, biological systems kick in to counter that loss. They slow our metabolism by reducing the amount of energy we expend doing everyday activities. Our stomach releases more hormones to heighten our hunger and desire to eat. Our digestive system and fat stores release fewer satiety signals so that our brain is slower to realise we are full.”
And doubling down on willpower does little to help. “It’s not due to a lack of willpower,” says O’Shea. “It’s because restricting calories affects how the body controls appetite, hunger, cravings, and body weight. The body reacts by altering metabolism, increasing food intake, and regaining weight.”
Impact of dieting on health
Not only is dieting ineffective, but there’s also evidence that restricting our food intake can undermine our physical and mental health. A 2010 University of California study showed that dieting triggered an increase in the stress hormone cortisol in previously healthy women.
“Stress hormones can affect a wide range of health concerns, from cholesterol to mental health,” says Flood. “They can also contribute to weight gain.”
Executive function suffers too, with a 2005 study from Flinders University in Australia proving that dieters performed more poorly in memory tasks than non-dieters.
Yo-yo dieting (the cycle of dieting, losing weight, regaining it, and then dieting again) is even more detrimental, says Flood. “It’s been shown to have a worse impact on cardiovascular health than staying at a stable weight at a higher body mass index. It’s also a significant risk factor in the development of eating disorders.”
A lack of willpower is often cited as why people don’t succeed at dieting. This idea angers Flood. “It sends the message that any inability to lose weight is the fault of the individual, rather than the fault of other factors, including unstainable diets,” she says.
Dr Judson Brewer is a professor at the Brown University School of Public Health in America and researches how our brains form negative habits.
“The idea that all we have to do is focus on the behaviour we want to change and use our willpower to change it is a great one,” he says. “It means we can simply choose to eat foods like salad instead of foods like cake. But we all know that it’s not as easy as thinking our way out of a behaviour, of suddenly changing the way we eat forever. Our willpower can’t really help us to break bad habits and make new ones.”
What will help, though, is understanding how our brain operates. “Then we can work with it instead of fighting against it,” says Brewer.
“If a behaviour is rewarding, we’ll do it again. If it’s not, we’ll stop doing it. To change our behaviour, we have to focus on the felt experiences of the rewards of that behaviour.”
Chocolate cake is a good example, says Brewer. “Eating chocolate cake is rewarding but eating one slice is different to eating three. There’s a point at which it no longer gives us pleasure, a point when our body signals we’re eating too much. If we pay attention and increase our awareness of how a behaviour feels and when it stops being rewarding, our brain will help us to break bad habits.”
These habits could be anything from bingeing on dessert, snacking while watching TV, or grazing all day.
“We can only break these habits through awareness of how they make us feel,” says Brewer. “Over time and with practice, that awareness will help us to enjoy our chocolate cake, notice when we feel full, and stop us from overindulging. We can quit relying on willpower, which doesn’t work anyway.”
He is promoting a form of mindful eating (which is similar to intuitive eating). This is based on encouraging mindful awareness of how we eat and becoming aware of physical hunger and satiety cues that guide our decisions to begin and end eating.
Is comfort food comforting?
Mindful eating is gaining scientific approval. In a study Brewer carried out a Brown University in 2018, he found that mindfulness training reduced craving-related eating by 40%.
It appears to be beneficial to our health, too, with a 2021 Columbia University review showing that mindful eating resulted in at least one benefit for metabolic or heart health, such as improved glucose levels, lower cholesterol, or improved blood pressure.
It may support better mental health. A 2014 review by Kent University in America found that participants who practised mindful eating showed improved psychological health, including less depression, increased self-esteem, and better quality of life.
The team behind RTÉ’s Operation Transformation has recognised how helpful a mindful eating approach can be in changing our attitude to food. Dietitian Aoife Hearne advises everyone who follows her healthy eating plan to complete a mindful eating questionnaire first. This encourages them to become more aware of the different factors that play a part in how they eat.
It may be growing in popularity but how sustainable is mindful eating when we’re sad, tired, or lonely? When all we want is the comfort of a tub of ice cream?
Mann has a surprising answer to this question: comfort food may not be that comforting. “People give it credit for mood improvements that would have occurred even if they hadn’t eaten it,” she says.
“Because people eat comfort food and feel better, they assume comfort food caused their better mood. That’s not the case.”
In 2014, she was involved in a study that found comfort food had little impact on mood. Participants watched sad movies. Some were then given their comfort food of choice, and others were given non-comfort foods, while a third group was given no food. The result? Everyone felt better. Food or no food, comforting or otherwise, all that mattered was the passage of time.
No one denies that what we eat is important and matters to our overall health. As Bennett says: “having a relatively regular pattern of meals and snacks that reflect national healthy eating guidelines is the most balanced and healthful way to eat”.
Getting our five a day even has an impact on our mental health. In 2016, a University of Queensland Australia study of 12,385 adults found that an increased fruit and vegetable consumption was predictive of increased happiness, life satisfaction, and wellbeing. It seems that we feel good when we eat well.
What the advocates of mindful and intuitive eating argue is that we feel even better when we move away from the deprivation and restriction model of dieting to rediscover our connection to our bodies and once again take pleasure in food.
“The bottom line is that dieting doesn’t work,” says Flood. “Intuitive eating encourages us to listen to our own body cues when it comes to hunger, fullness, and satisfaction. It focuses on making peace with food and respecting your body, rather than continuing the constant battle of dieting.”
How you eat is as important as what and how much you eat, says O’Shea. “Health is not a number on a scale and healthy eating is for everyone, regardless of their body size. There is no one-size-fits-all diet for weight management. It’s far better to choose an eating pattern that supports your health and that can be maintained over time rather than a short-term diet.”
We need to shift our focus away from body weight and towards health. “Weight is just one part of the jigsaw of our health,” says Bennett. “There are many other physical and mental pieces. When we talk about health as a society, it’s important that a balance is achieved and that we don’t disproportionately address body weight, which is only ever one part of the picture.”
Mindful eating experiment
I think I have a reasonably balanced attitude to food and what I eat. But like every Irish woman, I have absorbed negative messaging from diet culture. My tummy is too big. My upper arms too. I could always do with losing some weight.
I was interested in seeing how eating mindfully for a week, or at least trying to, might change my attitude to how I eat. I decided to take Dr Brewer’s advice and start by checking in with my body every time I ate, noticing how hungry I was and then pausing while eating to check if I was still hungry or full.
Brewer also recommends observing the textures and colours of foods and noticing how they smell and taste.
It sounds simple, doesn’t it? But it proved to be much more difficult than I thought.
I’m a busy working mother and I’m also the cook for the family. My days are pretty hectic right up to dinner time every day.
The day I started this experiment was a typical one. I had been rushing from the moment I got out of bed and by the time I got dinner ready and sat down to eat it, all thoughts of eating mindfully had disappeared. I was shovelling the food mindlessly into my mouth.
Suddenly, I remembered what I was supposed to be doing (I’d put up a reminder on the fridge). I took a deep breath and deliberately slowed my pace. I focussed my attention on the taste of the food in my mouth and how it felt. I made sure I put my fork down between bites and stopped to consider how full I was at regular intervals.
Over the course of the week, I found it difficult to remember to do this. It has yet to become a habit, but I can see how it could become one over time.
In 2021, Dr Brewer carried out a study to see how long it took for mindful eating to become a habit. He found that it took at least ten tries and as many as 38. I’m guessing that I’m at the upper limit of this range, but I’ve committed to reshaping my eating behaviour. When I do succeed, I enjoy my food more and I’m less likely to overeat.
The most important thing this experiment has taught me is that I’m living my life at too fast a pace these days. I need to slow down and slowing my eating is just the start of it.