Strength training on GLP-1s: what a trainer gets right and wrong

What did @jade.smiith actually say?

The claim is simple and loud: if you are not strength training, you are accelerating your risk of dementia, osteoporosis, and type 2 diabetes. She also made a specific neurological claim, that "the stronger your legs are, the thicker the folds in your brain." The overall framing is that skipping resistance training is "the most detrimental thing you can do for your health and wellness." That last line is where the wheels start to wobble.

To be fair, the core message is not wrong. Resistance training has real, well-documented benefits for bone density, insulin sensitivity, and cognitive function. But the way she delivered it collapsed a genuinely complex body of evidence into something closer to a health scare tactic. Overstating certainty in fitness content is its own kind of misinformation, even when the underlying behavior being promoted is beneficial.

Does the science back this up?

Partly, yes. The leg strength and brain health connection is real, but the "thicker folds" framing is an oversimplification of actual research. A 2015 twin study by Steves et al. in Gerontology found that greater leg muscle fitness was associated with better cognitive aging over ten years. The mechanism likely involves BDNF (brain-derived neurotrophic factor) release during muscle contraction, not a direct structural thickening of cortical folds per se.

On osteoporosis, the evidence is strong. Resistance training increases bone mineral density, particularly in postmenopausal women (Kohrt et al., 2004, Medicine and Science in Sports and Exercise). For type 2 diabetes, a 2012 meta-analysis by Strasser et al. in Sports Medicine confirmed that resistance training improves glycemic control and insulin sensitivity independently of aerobic exercise. So the disease associations she listed are not fabricated. The problem is she presented them as near-certain outcomes of not lifting, which the evidence does not support at that level of certainty.

What did they get wrong (or right)?

She got the general direction right. Resistance training is underutilized, especially among women, and the downstream health consequences of low muscle mass are real and underappreciated. Credit where it is due.

What she got wrong is the absolutism. Saying not strength training is "the most detrimental thing you can do" ignores smoking, sleep deprivation, ultra-processed diets, sedentary behavior broadly, and chronic stress, all of which have substantial mortality and disease data behind them. A 2018 Lancet analysis (Lear et al.) found physical inactivity broadly, not specifically the absence of resistance training, was associated with increased cardiovascular mortality. Walking, swimming, and other movement forms also confer significant protection.

The "proven" language around dementia risk is also oversold. Associations exist. Causation is harder to establish. The brain fold claim specifically is a loose paraphrase of research that talks about cognitive performance and brain volume, not cortical fold thickness as a direct outcome of leg strength. That distinction matters when you are presenting something as proven science to 131,000 viewers.

What should you actually know?

Resistance training is one of the most evidence-backed interventions for healthy aging, and the creator is right that it is underused, particularly among women who are often steered toward cardio-only routines. The risks of sarcopenia (age-related muscle loss) include falls, fractures, metabolic dysfunction, and reduced independence. Those risks are real.

But the framing that this is binary, either lift weights or accept decline, is not how physiology works. Any progressive resistance against muscles, bodyweight training, resistance bands, physical labor, counts. The American College of Sports Medicine recommends two or more days per week of muscle-strengthening activity for adults. You do not need a gym membership.

For people on GLP-1 medications like semaglutide or tirzepatide, this conversation is especially relevant. GLP-1 drugs drive meaningful weight loss, but studies including a 2024 analysis published in the New England Journal of Medicine (SURMOUNT-1 extension data) showed that a significant portion of weight lost on tirzepatide included lean muscle mass. Resistance training during GLP-1 treatment is not just a nice add-on. It is a clinical priority to preserve functional muscle and metabolic health.

Bottom line

The creator's enthusiasm is warranted. The certainty is not. Resistance training is genuinely important, the dementia and bone density science has real grounding, and the focus on women is appropriate given how underrepresented they are in strength training research and culture. But "the most detrimental thing you can do" is a claim that does not survive contact with the actual mortality literature. Take the message, not the hyperbole.