Dr Federica Amati, head nutritionist at Zoe and bestselling author, has issued a stark warning about the dangers of using GLP-1 medications—typically prescribed for type 2 diabetes—for cosmetic weight loss. She recounts extreme side effects documented in case studies, including scurvy, psychotic episodes, and hospital admissions for suspected dementia or psychosis. The underlying cause, she explains, is acute malnutrition of the brain. "If you're taking GLP-1s for cosmetic reasons, you're putting yourself at real risk of chronic under-nutrition," she says. "You're missing key micronutrients and if you chronically underfeed your brain, you could even have psychotic-like episodes." Additional risks include loss of skeletal muscle mass and bone mineral density.
New Book Addresses GLP-1 Nutrition
Amati's new book, The Appetite Reset, serves as a comprehensive guide to eating before, during, and after GLP-1 use. It focuses on protecting metabolism, restoring appetite signals, and building a sustainable relationship with food. The timing is critical: new data from The Food Foundation reveals that an estimated 8.25 million people in the UK have taken, are taking, or are considering GLP-1s. Amati expresses deep concern over the drugs' availability. "I've never seen something like it," she says. "They've bypassed normal prescribing. You would never be able to just fill in an online form and get, for example, anti-hypertensive drugs on Instagram." The surge in demand has outpaced NHS capacity, raising safety concerns about unsupervised use and long-term health outcomes.
Medicine, Not a Lifestyle Hack
"For some patient groups, the benefits outweigh the risks," Amati acknowledges. "But people microdosing and taking it willy-nilly are actually just playing with fire. We have no idea if it's a good idea. These drugs play in a network of hormones; they amplify one signal [to signal fullness] but in the body there's never just one effect. GLP-1 receptors exist across the brain, guts, pancreas, liver—they are all over the place. We don't know what the other downstream effects are. So it's really, really important that we treat them like medicine, not a lifestyle intervention."
Pre-Treatment Phase: Priming the Body
For those who proceed with GLP-1s, Amati outlines critical nutritional guidelines. The pre-treatment phase involves smoothing out gut, liver, and pancreas function. "Introducing GLP-1s across systems that are already a bit cranky and not working well is likely to have a less smooth outcome than if they're a little bit primed," she explains. "It's about feeding your gut well, restoring gut barrier function and reducing constipation if you have it." The key is gradually increasing fibre intake to allow the body to adjust. Starting healthy eating habits before treatment is also advisable. "When you start the medication, you will likely have nausea, constipation, reflux and bloating," she says. "So if you've prepared your system before you start, you're much more likely to be able to persevere and the medication is more likely to work at a lower dose, which is what we want during treatment."
During Treatment: Nutrient Density and Protein
During GLP-1 use, Amati advises focusing on nutrient density and adequate protein intake, coupled with resistance training. Hydration is critical, as is having small regular meals at set times. "If you don't have a schedule in place, it's easy to just think, 'Oh, I'll skip that meal', but you can't afford to do that because your food intake is often slashed by up to 40 to 50 per cent," says Amati.
Post-GLP-1s: Preventing Weight Regain
Amati reports that around 60 per cent of people stop taking the drug within a year. "When you look at interviews with the pharma companies, they make out that it's treatment for life," she says. "But when you look at the data, it's clear that most people don't last longer than a year on it." She also states that around 75 per cent of people regain about 75 per cent of their weight after stopping the drug, emphasizing the need to understand biology. "Your body is just trying to get things back to normal," she explains. "It's not that you've failed, it's just that your body is like, 'There's food again, let's eat it'." Her post-GLP-1 dietary advice focuses on high-volume, low-energy density foods that stimulate satiety signalling—such as kale, cauliflower, and tofu. "You're looking for foods that have the capacity to fill you up but also plenty of fibre, as that's what helps to release GLP-1s and other satiety hormones later in the colon," she says. Ultimately, Amati stresses that weight loss is not the sole measure of success. "A lot of people do come off the drug and put the weight back on. So we need to be really mindful that weight loss is not the only success of the drug when it's used properly. It's about trying to improve metabolic and long-term health and, if you can, during the window you're taking the drug, changing the way you think about food."
