Weight-loss medications such as semaglutide and tirzepatide (marketed under names including Wegovy, Ozempic, and Mounjaro) have become some of the most talked-about treatments in recent years. Some are hailing them the biggest breakthrough in medicine for decades and for many people living with obesity they can be life-changing.
These drugs mimic the naturally occurring hormone GLP-1, which regulates appetite and blood sugar, helping people feel fuller for longer and reducing overall calorie intake. Clinical trials show they can lead to substantial weight loss, often transforming the health of people with obesity or metabolic conditions.
However, emerging research suggests that a critical component of care is often overlooked, nutrition support. A new systematic review led by researchers at the University of Cambridge and UCL found that many people taking GLP-1 medications receive little to no structured dietary guidance alongside their treatment.
Patients naturally eat less while taking GLP-1s because they significantly reduce appetite, but that doesn’t automatically mean they are eating well. Without professional guidance, there is a risk of nutritional deficiencies, inadequate protein intake, loss of lean muscle mass and insufficient vitamins and minerals. These issues are particularly concerning if the reduced calorie intake is sustained over weeks or months without careful monitoring. Fatigue, weakened immunity and longer-term metabolic consequences can all result, potentially undermining the very health benefits that weight loss medications are intended to deliver.
The Rise in Accessibility
In the UK, GLP-1 medications are already widely used, with prescriptions climbing rapidly over the past year.
According to a large nationally representative survey conducted in early 2025 in Great Britain, an estimated 2.9 % of adults reported using a GLP‑1 or GLP‑1/GIP medication to support weight loss in the previous year. When extrapolated to the wider population (about 53.7 million adults), that equates to approximately 1.6 million adults taking these medications for weight loss. Of those, around 1.7 % of adults (~910,000 people) were using GLP‑1 drugs exclusively for weight loss rather than for other medical reasons like diabetes. Put in context, this means roughly 1 in 35 UK adults had used a GLP‑1 or related medication for weight management in the last year.
A stronger dose of Wegovy has recently been approved, and with greater media coverage and growing awareness, these drugs are becoming accessible beyond specialist clinics.
While this broader availability may help more people achieve weight loss, it heightens the urgency for integrated nutrition support. As more people self-manage their medications or access them through private channels, the risk of nutrient gaps rises. Appetite suppression may make it tempting to skip meals entirely, rely on convenience foods or eat poorly balanced meals, all of which increase the chance of unintended consequences.
In early 2026, pharmaceutical company Novo Nordisk launched the first ‘pill’ version of its GLP‑1 weight‑loss drug Wegovy in the United States, priced significantly lower and available through major pharmacies and telehealth providers, a shift that removes the need for injections and could broaden access to this class of medications even further.
Nutrition Matters as Much as Weight Loss
A new review in The BMJ shows that people who stop taking GLP‑1 weight‑loss medications like semaglutide and tirzepatide tend to regain most of the lost weight within around 1½–2 years after stopping treatment, often more quickly than after stopping diet‑based programmes, underscoring why strong, sustainable dietary habits are essential for long‑term health and weight maintenance.
GLP-1 medications are powerful tools, but weight loss alone is not the whole picture. Lean muscle mass is metabolically active tissue that supports long-term weight maintenance and metabolic health. If calorie intake drops too low or protein intake is insufficient, people risk losing muscle as well as fat, which can slow metabolism and affect strength, energy and immunity.
Micronutrients, including iron, B vitamins, vitamin D, calcium, magnesium, and zinc, are also at risk. Many of these nutrients are harder to obtain if total food intake is low or if diet quality is compromised. A patient might feel satisfied with smaller portions, but the diet could still be lacking in essential vitamins and minerals. Over time, deficiencies can emerge, leading to fatigue, poor concentration and even long-term health issues.
Practical Guidance for People Using Weight-Loss Drugs
For anyone considering or currently taking weight-loss medications, the Cambridge research emphasizes the importance of professional support. Here are some practical considerations:
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Work with a qualified nutrition professional
A nutritional therapist or dietitian can help design meal plans that meet protein, vitamin, and mineral needs, even with a reduced appetite. -
Focus on nutrient-dense foods
Small meals should prioritize lean protein, healthy fats, whole grains, fruits, and vegetables. Quality matters more than quantity. -
Don’t skip meals entirely
Even if appetite is low, splitting intake into smaller, frequent meals or snacks can ensure nutritional requirements are met. - Combine lifestyle support
Medications work best when paired with sustainable lifestyle changes, including physical activity, sleep and stress management.
Weight-loss medications such as semaglutide and tirzepatide are powerful and increasingly accessible tools in the fight against obesity. They can transform health and quality of life when used appropriately. But medications are not a silver bullet, without proper nutrition support, patients are at risk of deficiencies, muscle loss, fatigue and other unintended consequences.
The Cambridge study highlights a clear message: weight-loss drugs must come with structured dietary guidance.
In short, medication can suppress appetite, but it can’t replace the nutrients your body needs to thrive.
References
Wegovy to launch stronger dose weight-loss jabs as UK usage set to soar – Yahoo News UK