GENERAL MEDICAL NEWS
The staff of The Reproductive Times here offers brief referenced notifications on interesting general medical and scientific news with broad relevance to reproductive medicine and biology. Some of these news items may become subjects of more detailed reporting in The Reproductive Times on later occasions. The purpose of these short notifications is to give readers the opportunity to immediately find more detailed information by looking up the reference of the notification.
Obesity and infertility in women and men
Obesity has become a public health challenge in women and men. In women it is associated with reduced fertility and infertility as well as with an increased miscarriage risk. In men it is also associated with decreased fertility and infertility. A recent study in JAMA Network Open reported on the association between preconception BMI in both partners with time to pregnancy and/or miscarriage (1).
The median age of studied women was 31.6 years, and their median BMI was 23.5. Among men age was 33.4 years and BMI 24.9. Higher BMI in women and men was associated with lower fecundability. As expected, women with overweight and obesity had lower fecundability compared with women with normal weight. Moreover, compared to normal weight, underweight, overweight, and obesity were associated with increased odds of subfertility. In men this applied only to obesity. In addition, women with overweight and obesity also demonstrated increased miscarriage risk in comparison to normal weight women.
All of this is, of course, nothing new. But it reinforces the concept of weight loss as a fertility treatment, which we at the CHR have started emphasizing since GLP-1 receptor agonist drugs have come on the market. Much more on all of that below.
Reference
1. Boxem et al., JAMA Network Open 2024;36157
What is new regarding diets?
Are Western diets killing us?
Two Austrian academic internists published an interesting paper in Nature Medicine in which they argue that Western diets basically kill us. More specifically, they suggest that “westernization,” defined as industrial, cultural, and dietary trends, has paralleled the rise on non-communicable diseases around the world. After reviewing the literature in support of their thesis, they conclude that healthcare professionals and societies must react today to the detrimental effects of the Western diet to bring about sustainable change and improved outcomes in the future (1).
Not in any way desirous of defending Western diets, one is left wondering why, if it is only Western diets? Japanese diets, for example, have a much higher incidence of gastric cancers (attributed at least in part to more cases of gastritis (2)), which they lose once they immigrate to the West. Chinese diets seem to overwhelm China’s health system, with over a fifth of adults being overweight and experiencing large increases in hypertension, stroke, and adult-onset diabetes (3). In other words, it is not only the Western diet!
And how about intermittent fasting?
“Time-restricted eating,” as these diets are also called, has become very popular. A new study in the Annals of Internal Medicine now, however, suggests that the possible effectiveness of these diets may have different causes than previously assumed: It may not be directly due to time-restricted eating but may be the consequence of smaller caloric intake when people restrict eating to only certain time periods (4).
This in other words was a purely mechanistic study which tried to determine whether times when people ate their meals mattered, with no attempts to control for calories of those meals. Preliminary, one of the most interesting conclusions from these findings, is that while these kinds of diets do not lead to bigger weight loss than other diets, they appear to save individuals from having to count calories (5), which may be one reason why these diets have become so popular. In the end, it always comes down to calorie intake (and, of course exercise, etc.). Though this kind of diet did not prove to be more effective than other diets, it may be more patient friendly.
References
1. Adolph TE, Tilg H. Nat Med 2024;30:2133-2147
2. Naylor et al., Gut 2006;55(11):1545-1552
3. Popkin BM. Healt Aff. (Millwood). 2008;27(4):1064-1076
4. Lin et al., Ann Int Med 2024;176(7): https://doi.org/10.7326/M23-0052
5. Varady KA, Oddo VM. Ann Intern Med 2024;177(5):672-673