Dieting and “lifestyle programs” can feel so seductive in a culture that tells you your body is wrong and needs to be fixed. But what does science actually say about dieting for weight loss? Operates? Is it sustainable? Does it improve our overall health? We dive into all that and more in today’s post.Content warning: references to stigmatizing language about weight used in research, weight loss numbers
New Year, New Me messages are rampant at the start of the year and with that comes an onslaught of New Year’s resolutions and nutrition company marketing in full force.
I’ve heard January referred to as “National Diet Month” because so many diet / wellness / “lifestyle” companies (or whatever they call themselves these days) are rampant at this time of year and many people are especially vulnerable to their marketing . messages entering the new year.
What the $77 billion diet industry doesn’t tell you is all the research that shows diets don’t work long term. Because their value is based on repeat customers – the same people who try their program over and over and over again.
It’s helpful to know what the scientific literature says about diet and weight loss, but even more important (IMO) than the research is YOUR lived experience. Have diets worked for you in the past? How long did they work? Have you finally gained the weight back? Did the diets/lifestyle programs feel sustainable to you? Why or why not? You know your body best.
Diet and weight loss research
A 2007 review of the scientific literature on diet and weight loss by Mann et al. found that only 14 research studies looked at weight loss outcomes after 4 years or more. This means that all other dieting and weight loss literature has a very short-term follow-up (usually 1 year). These study designs benefit the diet industry because we know that diets work in the short term, but anywhere from two to several years, most people regain the weight.
The review found that of the studies they looked at, participants lost about 10-65 pounds. At follow-up, most of the weight had been regained. Results ranged from a net loss of 15lb to an 8lb weight gain from where they started.
30-64% of participants ended up at or above their starting weight before the diet.
Only 9% of participants ended up with a BMI of less than 35. And those who lost more than 15% of their weight actually doubled their mortality risk.
A 2018 general review of meta-analyses on weight loss interventions found that “there is no high-quality evidence to recommend treating ‘obesity’ with a specific non-surgical or non-pharmacological intervention among many available”. AKA we don’t have good evidence to recommend dietary or lifestyle interventions for weight loss.
Naturalistic studies (where you observe people in their natural environment and record behaviors) have concluded that diet is actually a predictor of weight gain. So diets not only don’t work but also predict weight gain. A number of meta-analyses and comprehensive reviews have reported the same results – that lifestyle interventions actually lead to weight gain, especially with long-term follow-up.
Other reviews have shown that 3-5% weight loss is possible for years afterwards if all aspects of treatment are maintained. To give this more context, that would be a 6-10 lb weight loss for a 200 lb person. The health benefits of this type of moderate weight loss are unclear. And most people are looking for 30% weight loss, not 3-5%.
Are there health risks associated with weight due to weight cycling?
Studies show that weight cycling (weight loss, weight gain, rinse and repeat) is a risk factor for diabetes, dyslipidemia, poorer self-esteem, insulin resistance, hypertension, and visceral fat.
A 15-year study showed that the highest death rate was in people who lost weight and not those who gained weight or remained stable. That too other studies it shows us Weight cycling can be worse for your health than staying at/maintaining a higher weight.
What if the health risks we see associated with weight are actually due to repeated attempts to lose weight and the stress it puts on the body rather than actual body size?
We know that health-promoting behaviors (exercise, eating more fruits and vegetables, getting enough sleep) can reduce mortality risk regardless of any weight changes. Yes correctly. You can improve your health indicators without losing weight.
It is also important to consider how weight stigma or anti-fat bias plays into the association data we see between higher weights and worse health outcomes. It has been reported in the literature that “bias can reduce efforts to engage in healthy lifestyle behaviors through negative emotional distress and unhealthy eating patterns.”
It’s also worth noting that all studies on weight and health risks are correlated. And when you learn how to read and analyze the research, the one thing that is always emphasized is “correlation does not equal causation”. We cannot say that weight causes chronic disease – there is no literature to support this.
If you look at all the data on smoking/tobacco use and lung cancer and see that there is a correlation between them with yellow teeth and lung cancer, you would never say yellow teeth caused the cancer, you would say it is a side effect of smoking. Yellow teeth are not a behavior.
Just because weight is associated with chronic disease does not mean it is the cause. Weight is also not a behavior.
“Overweight” BMIs have the lowest risk of mortality
We’ve been sold the belief that being “overweight” is bad for your health. What we haven’t heard is this studies show Being ‘overweight’ has a lower risk of mortality compared to ‘normal weight’. A BMI of 30-34.9, referred to in the medical field as “obese category 1” has also been shown to have no higher risk of mortality compared to “normal” weight.
Why isn’t anyone talking about the protective effect of being “overweight”? Because that wouldn’t be good for all the pharmaceutical companies that sell weight loss drugs and the diet industry that sells their lifestyle programs.
BMI is bullshit anyway, but I could write another whole blog post on that topic, so I’ll save that for another time.
Bibliographical references:
Solmi, M., Köhler, CA, Stubbs, B., Koyanagi, A., Bortolato, B., Monaco, F., … & Carvalho, AF (2018). Environmental risk factors and non-pharmacological and non-surgical interventions for obesity: A general review of meta-analyses of cohort studies and randomized controlled trials. European Journal of Clinical Investigation, 48(12), e12982.
Lissner, L., Odell, PM, D’Agostino, RB, Stokes, J., Kreger, BE, Belanger, AJ, & Brownell, KD (1991). Variability of body weight and health outcomes in the Framingham population. New England Journal of Medicine, 324(26), 1839–1844.
Tolvanen, L., Ghilotti, F., Adami, H.-O., Ye, W., Bonn, SE, Bellocco, R., & Lagerros, YT (2023). Prospective study of weight loss and all-cause, cardiovascular, and cancer mortality. Scientific Reports, 13(1), 5669.
Mulligan, AA, Lentjes, MAH, Luben, RN, Wareham, NJ, & Khaw, KT (2018). Weight change and 15-year mortality: results from the European Prospective Investigation on Cancer in Norfolk (EPIC-Norfolk) cohort study. European Journal of Epidemiology, 33(1), 37–53.
