All about nutrition, obesity drugs, and food

That “food is medicine” is an increasingly frequently heard phrase in medicine that also applies to fertility. A prominent current subject is, for example, weight loss with GLP-1 receptor agonist drugs since obesity is becoming an increasingly frequent co-diagnosis in infertility practice. 

A New Definition of Obesity 

The medical journal Lancet Diabetes & Endocrinology published a report by a global commission of experts, calling for a radical shift in how obesity is diagnosed. A key change involves less reliance on the body mass index (BMI) (1). In another important update, the Commission identified when obesity is a risk factor (preclinical obesity) and when it represents a stand-alone illness (clinical obesity).

These changes arose from the recognition that, despite obesity affecting nearly one-eighth of the world’s population (2), a global consensus on its classification and definition had not been established. Individuals living with obesity have different health profiles and needs but are often discussed as a single entity, defined by one parameter (BMI), or not discussed at all. The Commission included 56 leading experts from high-income, middle-income, and low-income countries and has been endorsed by more than 75 international medical organizations with a stake in obesity and the care of those affected.

The new, evidence-based definition distinguishes “clinical obesity,” a chronic, systemic disease state directly caused by excess adiposity, from “preclinical obesity,” a condition of excess adiposity without current organ dysfunction or limitations in daily activities but with increased future health risks. Given the limitations of BMI, the Commission recommends using additional measurements of body size (waist circumference, waist-to-hip ratio, or waist-to-height ratio) alongside BMI to define obesity.

To start, current epidemiological data on obesity prevalence, which rely solely on BMI, must be updated to reflect obesity as a spectrum of medical presentations. Preliminary audits of available databases are already underway and suggest that a substantial number of people with obesity do not meet the criteria for clinical obesity. However, these analyses are limited by the use of historical, incomplete data. Therefore, databases must include a fuller picture of an individual's healthcare status. Furthermore, there is substantial scope for the stratification of clinical obesity into different subtypes, potentially based on clinical presentation or pathophysiology, which should enable better management and understanding.

References

1.      Rubino et al., Lancet Diabetes & Endocrinol 2025;

2.      NCD Risk factor Collaboration. The lancet 2024;403(10431):P1027-1050

A Lot of Nutritional Research Data May Have to Be Redone

A recent study in Nature Food attracted considerable attention because it suggested that prior survey-based studies linking allegedly consumed diets to health outcomes may be fatally flawed due to inaccuracies in the reporting of food intake by study subjects. Applying a validated equation to two large datasets (National Diet and Nutrition Survey and National Health and Nutrition Examination Survey), the investigators found that the level of misreporting was greater than 50%. The macronutrient composition from dietary reports in these studies was systematically biased as the level of misreporting increased, leading to potentially spurious associations between diet components and body mass index (1).

A Commentary article in Science recently discussed the conclusions the nutrition field must draw from this study (2). One cited expert concluded, “We’ve got to try and use new technologies to do better.” In other words, a significant portion of what we currently believe links certain foods to certain diseases is probably inaccurate. This paper, of course, also explains why “diet data” have been so contradictory.

A good example may be a recent article in the European Heart Journal, which concluded that drinking coffee in the morning may be more strongly associated with a lower risk of mortality than drinking coffee later in the day (3). While even the general information provided by these Chinese investigators—suggesting that coffee drinking reduces mortality—is interesting, we would, considering the previously discussed publication, not place too much emphasis on this paper.

References

1.      Bajunaid et al., Nature Food 2025;6:58-71

2.      Offord C. Science 2025;387:6732:352

3.       Wang et al., Europ Heart J. 2025

Can a keto-diet restart and/or realign menstrual cycle for women with obesity?

This is at least what, according to a recent paper in PLOS One, research at Ohio State University suggested (1). A recent summary of the paper by Healio summarized the study very well: (i) Ketosis, with and without exogenous ketone supplementation, resulted in realigned or restarted menses. (ii) Both ketogenic and low-fat diets, after six weeks, resulted in weight loss, declines in BMI, positive changes in body composition, and improved insulin sensitivity.

Moreover, compared with a low-fat diet, nutritional ketosis – with or without exogenous ketones – can positively impact self-reported menses (the fact that menses is self-reported is, of course, also important here), restarting or realigning menstrual cycles. The first author of the paper in the Healio article was quoted as noting that a 33-year-old participant in the study, who had never before experienced a menses, experienced her first menses after just five days of being in nutritional ketosis (2).

References

1.      Kackley et al., PloS One 2024;19(8):e0293670

2.      Healio. December 11, 2024. https://www.healio.com/news/womens-health-ob-gyn/20241211/keto-diet-may-restart-realign-menstrual-cycles-for-women-with-obesity