As GLP-1 weight loss drugs like Ozempic and Wegovy continue to gain popularity, experts warn that rapid weight loss and severe calorie 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 drug’s effects on the brain may depend on whether the body is getting enough energy and nutrients during the weight loss process.
“The best way to think about this is the range 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 the most energy-intensive organ in the body.”
According to Wood, brain reserve—the physical quantity and integrity of brain tissue—follows a bell-shaped curve relative to the body’s available energy.
Excess energy from obesity, hyperglycemia, and metabolic disease can damage blood vessels and cause insulin resistance, which reduces the brain’s ability to recover.
In these cases, GLP-1 drugs may provide cognitive benefits by lowering blood pressure and improving blood sugar control.
However, Wood points out that the lower end of the energy spectrum poses its own structural risks to the brain. Since the brain relies heavily on constant fuel, an extreme caloric deficit forces the organ to consume its own tissue.
“There was a study that looked at the brains of people who ran marathons… because marathons are an energy-intensive sport, the white matter in the brain actually shrank during the marathon because the brain didn’t have enough energy… so it was eating its own white matter,” Wood said. He noted that the participants’ brains recovered after resting and refueling.
“It just shows that the brain does need energy, and if it doesn’t get enough, it shrinks in size.”
Muscle mass
Concerns about muscle loss when taking GLP-1 drugs are often subtle, Wood said. Some of the “lean mass” lost early is actually fat accumulated inside the muscles.
“So technically, your muscles will get smaller, but you won’t get weaker,” he told Fox News Digital. “And your muscle mass and function actually get better.”
However, risks arise when individuals taking GLP-1 drugs significantly reduce their food intake for an extended period of time. Wood warns that chronic dietary deficiencies can deprive the central nervous system of essential structural nutrients.
“You can end up going too far,” he said. “If you don’t eat enough, you’re not getting enough nutrients for your brain. So you’re not getting enough omega-3 fats, which we know are really important. You’re not getting enough iron and protein and all those things.”
Protecting the brain during weight loss
To protect brain health while losing weight, Wood recommends combining a weight loss regimen with resistance training twice a week to maintain functional muscle mass and stimulate brain growth factors.
In addition, Wood says ensuring you get enough core “neuronutrients” – including B vitamins (B12, folate, B6), vitamin D, iron and omega-3 fatty acids – can prevent long-term cognitive impairment.
“For most people, I think it’s beneficial to start, but you just have to make sure you don’t overdo it and you’ve got everything you need to get enough brain power now,” he advises.