If you aren’t among the subset of previously enlightened professionals then you may find the latest obesity research headlines shocking. The news that overeating doesn’t cause obesity confronts many deeply held beliefs about dieting and weight loss.
First, it’s important to understand the limitations of the research behind the headline. The paper published in the American Journal of Clinical Nutrition (Ludwig, et al., 2021) consists of a review of the energy balance model (EBM) of obesity along with the author’s proposal of an alternative explanation – the carbohydrate-insulin model (CIM). It includes no original research. Rather, the paper outlines limitations of the EBM models and sets up hypotheses arising from the CIM model. Therefore, the conclusions are primarily the opinions of the authors.
The debate behind this paper is well known within the weight loss industry, and the lead authors are well known for their work promoting their alternative carbohydrate-insulin model. You likely know this model too as it’s the basis for the popular “keto” and other low carb (carbohydrate) diets.
Secondly, it’s important to separate what is known about each of these models. It’s been known and accepted for years, if not decades, that the energy balance model of weight is inadequate to fully explain weight loss or gain. What’s important to understand is that how much we eat does matter, it’s just not the whole explanation behind our weight.
However, the alternative carbohydrate-insulin model is only one proposed alternative explanation and not settled science. In fact, there is research disputing, as well as refining, this model as well and on-going research on multiple other models of weight. The authors acknowledge this putting forth nine testable hypotheses and noting criticisms of their model.
One of the criticisms is that research confirms that weight loss is not greater from low carbohydrate diets in long-term trials. This has been confirmed in dozens of studies and meta-studies. Additionally, concerns about negative effects on health of high protein and high fat diets have not been adequately disproven. In the end, no diet has been proven to lead to long-term weight loss, and in fact, having been on a diet is one of the strongest indicators of weight gain.
A criticism not noted in the paper is that our understanding of insulin response has radically changed in recent years. Protein is now known to trigger insulin response when it was thought not to in the near past. And wearable blood sugar monitors are revealing that insulin response is highly individual, and often not what was predicted. Other factors including air pollution and stress are now known to trigger insulin response. Therefore, many of the ideas that people have about low carb dieting may be outdated or ineffective.
Also important to note is that many people are confused as to the label “low carb” or “carbohydrate.” Several sources of nutrition essential to health and longevity are carbohydrates – including all vegetables, fruits, beans, and whole grains. While cutting down on excess intake of cookies or crackers can be a positive for our weight, drastic reduction of carbohydrates is counter to what is known to be health inducing.
Another theory not discussed in the paper has to do with the ratio of Omega 3 to Omega 6 fat in our diet. Our modern food system provides an excess of Omega 6 fats which has been a long standing concern. Now new research shows the previously unknown value of stored fat in providing a source of Omega 3 affecting such things as fertility, cognitive ability, and our weight. According to this “alternative to the alternative” model, we will continue to gain weight and experience an inability to lose weight so long as the ratio of fat in our diet, and reflected in our body fat, is not in balance.
And, of course, not discussed at all is the contribution of genetic factors estimated to explain as much as 70% of what we weigh. Or that even laboratory animals in controlled food environments are getting fatter.
Where does this leave us? The bottom line is that, as concluded in this paper, overeating isn’t the only contributor to our weight. Unfortunately this piece of research doesn’t provide any further direction than what we already know which is that our weight is the result of multiple complex and inter-related factors.
Lisa Newman, MBA, MAPP is a positive psychology practitioner and health coach specializing in eating behavior and body acceptance. She is a certified mind body eating coach and certified intuitive eating counselor. You can find out more at WomenEat.com.