Even successful studies show how poorly dieting works
OPINION: Many people manage to lose weight, commentators and experts agree. But research still shows that lifestyle interventions don’t work well against obesity.
Seven out of 10 people in Norway are overweight or obese.
Many people need to lose weight.
A new Norwegian reality TV-show called 16 weeks of hell has recently sparked the debate on weight and weight loss in Norway. Six celebrities get expert help to lose weight and get in shape, with the help of protein shakes and expert guidance on fitness.
In the ensuing debate in Norwegian media, the claim that permanent weight loss is certainly possible has been repeated, refuted, and repeated again.
Of course it’s possible to lose weight.
There’s plenty of evidence both in research and in the population.
In fact, you may know someone who was once very heavy, but who went on a diet and has since had a normal weight.
But I'd say it’s more likely that you know people who have lost weight — often many times — and who are still just as big.
Because this is the consistent finding that emerges from the research on dieting and weight loss.
Numerous studies have been done on dieting, where people with obesity reduce their calorie intake and increase their level of physical activity — an approach that is called a lifestyle intervention.
The results tend to be something like this:
First, the majority of participants lose weight — how much depends on how extreme the programme is — and then almost everyone gains the weight back in a year or two.
A good reflection of this problem is a survey of participants from the American weight loss programme The Biggest Loser. Six years after they had participated in the TV series, only one of the participants had managed to keep the weight off. The rest had regained their lost weight.
A British study from 2015 showed that almost no one with obesity manages to reach a normal weight.
Less than one in a hundred with the mildest degree of obesity managed to lose enough to be considered normal weight. The same was true of only one in a thousand with severe obesity.
The vast majority weren’t even able to maintain a small amount of weight loss.
And it isn’t because people aren’t trying.
Half the world is on a diet
Recently, Ipsos conducted a survey across 30 countries and found that 45 per cent of the participants said that they were trying to lose weight.
A study from the USA from 2013 to 2016 showed the same trend: Half the population had tried to lose weight during the previous year.
Half the world is trying to lose weight, at the same time as the number of overweight and obese people is increasing in almost all countries.
And yet the myth persists that dieting is the way to go.
The Look AHEAD study has been cited in Norwegian media as an example of how many people succeed in losing weight.
And sure enough, the study has very good results compared to many other attempts at lifestyle intervention.
But does it show that a lot of people have succeeded in losing weight? I would argue that, on the contrary, it demonstrates how low the threshold is for what we call successful obesity treatment.
The Look AHEAD Study
The Look AHEAD study was conducted by a number of researchers at 16 different centres in the United States. They recruited over 5,000 participants with obesity and type 2 diabetes. The participants were motivated to make lifestyle changes, and were in good enough physical shape to implement the recommended measures. The mean age at the beginning of the study was 60 years and the mean BMI was 36.
The participants were equally divided into two groups.
The control group received regular diabetes treatment and three group meetings each year. There, they were given information and up-to-date advice on diet and physical activity for diabetic patients.
The lifestyle group, on the other hand, received a comprehensive plan.
The goal was to complete at least 175 minutes of moderate to intense physical activity each week, and to limit food intake to between 1,200 and 1,800 calories per day, depending on what they initially weighed.
0 to 6 months:
The participants had four meetings a month, one individual meeting with a therapist and three group meetings. Participants were given physical activity goals and meal plans with the right amount of calories and fat.
Participants were advised to replace two of the day's meals and one snack with weight loss products such as shakes and bars. These were given to them free of charge by the researchers.
7 to 12 months
Participants continued with one individual meeting and two group meetings each month. They were advised to replace one of the current meals with substitutes, which they continued to receive for free.
The participants who had not managed to lose weight were offered more intense treatment and weight loss medication.
Years 2 to 4
Participants received at least one monthly individual meeting and a follow-up by phone, letter or email. Those who needed it could have more meetings. Participants were still encouraged to use meal replacements, which remained free for the duration of the study. Refresher group meetings were also arranged over six to eight weeks, three times a year.
From year 5
Participants were still encouraged to attend monthly meetings with the therapist. They were also offered monthly group meetings, and encouraged to participate in two annual campaigns and refresher groups as in previous years.
Source: The Look AHEAD Study: A Description of the Lifestyle Intervention and the Evidence Supporting It
The Look AHEAD study is a masterpiece of a study.
The researchers worked hard to develop the best possible plan for weight loss, based on previous research results.
Thousands of motivated participants lost weight during the first year, and received extensive help to maintain weight loss for many years afterwards.
The offer was impressive, with frequent individual meetings, group meetings, follow-up telephone calls, refresher courses, meal plans, free powdered weight loss drinks, advice on exercise and offers of weight loss pharmaceuticals for those who struggled.
The treatment teams included diet experts, behavioural psychologists, exercise specialists and doctors.
So what were the benefits of this formidable effort?
After eight years, the participants had on average lost just under 5 per cent of their body weight.
A woman who was 165 cm and very severely obese, with a BMI of 40, would then have lost six kilos, from 110 to 104 kilos. She would still be considered severely obese with a BMI of 38.6.
A similar woman with slight obesity and a BMI of 30, would have lost four kilos, or gone from 82 to 78 kilos. She would now be considered overweight with a BMI of 28.7.
We also have to keep in mind that the control group — which was only given normal diabetes treatment and three annual information meetings — had also lost weight eight years later. They had an average weight loss of 2.1 kilos, although they had done less to exercise and cut calories.
Granted, this is an average, which means some of the participants lost much more. 11 per cent managed to lose at least 15 per cent of their body weight.
But even after such an achievement, someone who started with severe obesity would still be classified as obese.
In addition, as many as 26 per cent of the participants actually gained weight during the treatment.
Can we say that lifestyle interventions actually treat obesity, when the vast majority of participants still have obesity afterwards?
To put it in perspective: Imagine that you have eczema over large parts of your body. Your doctor gives you a foul-smelling cream that you have to apply to your body four times a day. After months, 80 per cent of your rash is still just as bad. And if you are a little sloppy with applying the cream, you are back to square one.
Would you find this helpful?
At this point, some will probably object that it’s not just the number of kilos people lose, but rather about preventing serious consequences from having obesity, such as type 2 diabetes, cardiovascular disease, sleep apnea and cancer.
Although many lifestyle intervention studies show poor results for weight loss, many researchers point out that even a little weight loss is linked to lower risk of these diseases, often measured in changes in the values of cholesterol, blood pressure and blood sugar.
This is not insignificant. But here too there are several issues.
For example, it’s unclear how beneficial a small amount of weight loss is for your health.
The Look AHEAD study is a good example. It was originally intended to investigate whether weight loss prevented heart disease. But the study was eventually ended when it became clear that the participants in the lifestyle intervention group developed as much heart disease as those in the control group.
A summary from 2017 suggests that the limit for useful weight loss is different for different problems, and varies from individual to individual.
It is also unclear how long the health effects of dieting last. Many studies show the body benefits during weight loss. But what happens in the years afterwards?
A Norwegian study on the effect of dieting on stiff blood vessels, for example, found that the positive benefits evaporated after a year.
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Healthier even without dieting
Another issue is that weight loss isn’t always necessary to lower the risk of disease. As the researchers behind the Look AHEAD study wrote:
There is reason to believe that increased physical activity can reduce the risk of heart disease and death, even without significant weight loss.
Several studies have also shown that a better diet can improve health without dieting.
If the goal of treatment is really to prevent disease, perhaps we should drop dieting altogether and find approaches that do less harm?
Because dieting exacts a toll on people who diet.
For many, dieting involves a lifelong struggle against strong physical urges such as hunger and food cravings, accompanied by a feeling of defeat, shame and remorse every time they give in.
Dieting casts long shadows over the bright spots of life, such as birthdays, Christmas, weekends and dinner with friends. An eternal battle against the body also makes it harder to like oneself and enjoy closeness with other people.
Not to mention the fact that our focus on weight can actually make people sicker and fatter.
Stigmatization is harmful
Because when commentators in the media constantly give the impression that dieting is a solution to obesity problems, they also send another message:
Fat people could be thin if they just bothered to try.
The commentators reinforce our mistaken belief that people's body size can tell us what they are eating and how much common sense and willpower they have.
When large sections of society think this way, it’s no wonder that people with obesity are stigmatized, discriminated against and mistreated by employers, health professionals and most everyone else.
A Swedish researcher concluded in 2017 that society as a whole is characterized by a contempt for obesity. And if there is one thing that is really not good for a person’s health, it’s being stigmatized.
In addition to causing mental and physical discomfort, stigma can ironically lead to more obesity.
Time to make an effort
I'm not saying it's impossible to lose weight and keep it off.
A few do it, and that's great. We should do more research to find out what characterizes these people, so that doctors and therapists can predict who may benefit from such treatment.
But years of studies, millions of people's experiences and tons of documentation show that dieting is a very ineffective solution for the majority of people with obesity.
So maybe it's time for us to stop believing that more of the same thing will suddenly give us better results, and rather intensify research on more effective forms of treatment.
It's really time for someone other than fat people to make an effort.
Now it's our turn — we who are slim or just worried about a little Christmas flab. It is our turn to pull ourselves together and do something about our own prejudices against big people.
Translated by Nancy Bazilchuk
Read the Norwegian version of this article at forskning.no