Dr. Gabrielle Lyon

Vaginal oestrogen demonstrably reduces recurrent urinary tract infections in postmenopausal women, with roughly a halving of the number of infections seen in randomised research. The safety for most women is also well established. However, the claim goes too far on two points: whether it also prevents sepsis has not been studied, and not every woman benefits to the same extent. Furthermore, this benefit applies exclusively to locally applied oestrogen, not to oral tablets.

Being overweight does indeed increase the risk of breast cancer, but that link has been most strongly demonstrated for breast cancer after menopause. The claim presents it as a general relationship between BMI and breast cancer, without that nuance. In addition, research indicates that abdominal fat is an independent risk factor that is separate from body weight alone, which means BMI is not the most complete measure of this risk.

Research shows that intermittent fasting has positive effects on, for example, insulin levels, weight and gut flora, but those benefits are far from equal for everyone. In healthy individuals, the evidence is thinner than in people with obesity or a metabolic disorder, and most studies are small and short-term. The claim that a fasting period of at least 12 hours produces clear health benefits therefore goes further than what current research broadly supports.

Research shows that both too little and very long sleep are associated with more illness and a higher risk of death, which supports the direction of the claim. However, the specific threshold of "more than 8 to 8.5 hours" is not defined that precisely in the literature reviewed: 8 hours is mentioned as a comfortable upper limit, without an exact figure for when long sleep becomes risky. The claim is therefore broadly correct, but the precise threshold goes beyond what the studies actually support.

Exercise demonstrably increases testosterone in older men, and losing weight improves various health markers from as little as a modest 5 to 10% weight loss. The idea that weight loss also improves testosterone levels is in line with this broader pattern, but for erectile function specifically, the available studies offer no direct support. The claim combines two effects that are each plausible on their own, but for erectile function the link with weight loss has not been demonstrated on the basis of the available evidence.

The claim that weight loss is accompanied by bone loss is well supported: losing weight later in life almost always leads to some bone loss, even in physically active people. Whether GLP-1 medications specifically cause bone loss in the hip and lumbar spine in the absence of exercise cannot be firmly established based on the available research. Strength training substantially limits bone loss during weight loss, but does not prevent it entirely, so the claim that exercise fully prevents bone loss during GLP-1 use goes beyond what the evidence supports.

Multiple studies consistently show that creatine in people over sixty, combined with strength training, improves muscle strength and muscle mass, which is relevant to sarcopenia. For bone density, however, the evidence is more mixed: strength training itself measurably increases bone density, but research does not support the idea that creatine makes an additional contribution to this. The claim is therefore partly correct, but the effect on bone density appears to be attributable to the training rather than to creatine as a supplement.

Research shows that greater muscle mass increases your ability to clear blood sugar and that this is the most concrete hormonal effect of muscle mass. The link with insulin sensitivity is therefore correct. However, the claim goes somewhat further than what the evidence firmly establishes: the specific mechanism of glycogen storage in muscles is not described in the literature reviewed, and the evidence for the effect on insulin sensitivity is reasonably strong rather than conclusively proven as a cause.