Rapid weight loss on popular drugs could ‘starve’ the brain, expert warns
As GLP-1 weight-loss medications like Ozempic and Wegovy continue to surge in popularity, experts warn that rapid weight loss and severe caloric restriction could deprive the brain of vital energy and nutrients.
Dr. Tommy Wood, a professor of pediatrics and neuroscience at the University of Washington, said the drugs' effects on the brain may depend on whether the body is getting enough energy and nutrients during weight loss.
"The best way to think about this is the spectrum of what we call energy availability," Wood told Fox News Digital at Strong NY, New York City's largest annual fitness and wellness festival. "The brain is your most energy-hungry organ in the body."
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According to Wood, brain reserve — the physical amount and integrity of brain tissue — follows a bell-shaped curve relative to the body's energy availability.
Excess energy caused by obesity, high blood sugar and metabolic disease can lower the brain's resilience by damaging blood vessels and contributing to insulin resistance.
In these cases, GLP-1 medications can provide cognitive benefits by lowering blood pressure and improving blood sugar control.
However, Wood noted that the lower end of the energy spectrum poses its own structural risks to the brain. Because the brain relies heavily on continuous fuel, extreme caloric deficits can force the organ to consume its own tissue.
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"There was a study that looked at the brains of people who ran a marathon ... because the marathon is so energy-intensive, the white matter in the brain actually shrank during a marathon because the brain didn't have enough energy … so it was eating its own white matter," Wood said, noting that the participants' brains recovered after resting and refueling.
"It just shows that the brain is really energy-hungry, and it will decrease its size if it's not getting enough energy."
Concerns about lean muscle loss when taking GLP-1 medications are often nuanced, Wood said. Some of the early "lean mass" that's lost is actually fat that had built up inside the muscles.
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"So technically, your muscles get smaller, but you don't get weaker," he told Fox News Digital. "And the quality and functioning of your muscles actually gets better."
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However, risks arise when individuals taking GLP-1 medications drastically reduce their food intake for extended periods. Chronic under-eating can deprive the central nervous system of essential structural nutrients, Wood warned.
"It is possible that you can end up going too far," he said. "If you're not eating enough, you're not getting the nutrients that are critical for the brain. So you're not getting in enough omega-3 fats, which we know are really important. You're not getting enough iron and protein and all those kinds of things."
To safeguard brain health while losing weight, Wood recommends pairing weight-loss regimens with resistance training twice a week to maintain functional muscle mass and to stimulate brain growth factors.
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Additionally, ensuring adequate intake of core "neuro-nutrients" — including B vitamins (B12, folate, B6), vitamin D, iron and omega-3 fatty acids — prevents long-term cognitive impairment, according to Wood.
"For most people, I think it's going to be beneficial to start, but you just need to make sure that you don't push it too far, that you're now getting enough of everything that the brain needs," he advised.