As GLP-1 medications become an increasingly common tool for weight management in the UK — with an estimated 1.6 million adults having used weight loss drugs between early 2024 and early 2025 — the conversation around weight loss has shifted dramatically.

With the NHS rolling out tirzepatide (Mounjaro) and online searches for “GLP-1” surging by 120% over the past year, millions are looking at these treatments to help manage their weight.

However, as a nutritionist, I’ve long believed that while these medications can play an important role, good nutrition remains an essential part of the journey. That’s why at PortionIQ, we partnered with Censuswide to survey 1,000 UK adults currently dieting to lose weight, including GLP-1 users.

The results — published in our new Nutrition Gap Report — reveal a trend we can no longer ignore: the emergence of a “nutrition confidence gap” among long-term users.

The nutrition confidence gap

When people first start taking GLP-1 medications, they often feel relatively optimistic about their choices, but that confidence tends to erode over time. Key findings from our report include:

A staggering 92% of GLP-1 users believe people managing their weight should receive more nutritional education and support.

Nutritional confidence drops significantly over time: 29% of those taking GLP-1s for two years or more lack confidence in their knowledge of essential nutrients.

Compared to new users: Only 12% of those taking GLP-1s for less than a month lack confidence in their nutrient knowledge.

Confidence in getting enough nutrients falls steeply: While 81% of new users feel confident they are getting enough nutrients, this drops to 57% among those on GLP-1s for two years or more.

Why long-term management is challenging

GLP-1 medications work effectively by suppressing appetite and slowing digestion, but this creates unique physiological hurdles. In our survey, 45% of GLP-1 users reported only being able to manage smaller portions. Furthermore, 44% experienced a reduced appetite, and 29% reported fatigue or low energy.

Side effects are also prevalent: only 8% reported experiencing none of the unwanted reactions included in our survey (such as nausea, constipation, and headaches), compared to 28% of dieters using other weight loss methods.

Meeting nutritional requirements — particularly protein — also becomes much harder. While expert guidance recommends at least 1.2 grams of protein per kilogram of body weight daily for GLP-1 users, 14% of users found it difficult to consume enough protein, compared with 9% of those using other methods.

Where are people turning for advice?

With 90% of UK patients currently accessing GLP-1s for weight loss privately or off-label (and only 9% taking them on the direct recommendation of a healthcare professional), users are seeking guidance from a wide variety of sources:

• GPs remain the most common source, consulted by 46% of users.
• Nutritional professionals follow closely at 26%.
• Family and friends provide guidance to 24% of respondents.
• Online and social channels are heavily relied upon, with 25% turning to online articles, 21% to social media, and 10% to influencers or content creators.

Nutrition as an ongoing journey

Nutritional support should never be a one-off conversation when starting a prescription; it needs to be an ongoing part of the weight management journey as people’s needs, eating habits, and confidence evolve.

Clear, trustworthy information can help individuals make informed choices around protein, nutrient-dense foods, and hydration—especially when portions are smaller and appetite is suppressed. Whether someone is using a GLP-1 medication or another weight loss approach, having access to practical, reliable guidance ensures they feel confident in meeting their nutritional needs every step of the way.

To read the full Nutrition Gap Report and explore our complete research methodology, visit the PortionIQ Nutrition Gap Report. 

 Mark Gilbert, nutritionist at PortionIQ, B.A.Sc (Nutrition), RNutr, CISSN  

Current Roles: Nutritionist for PortionIQ; Science Officer, TDMR Europe & Scientific Subcommittee  has been involved in nutrition and healthcare for over 30 years. He is a registered nutritionist and has held multiple certifications in sports nutrition, exercise science and pharmaceuticals. He is also currently Science Officer for TDMR Europe. Formerly, Mark was Vice Chair of the European Specialist Sports Nutrition Alliance, Director of Consumers for Health Choice, author, international speaker, on the Advisory Board and columnist for Muscle & Fitness, Flex and Muscle Insider magazines and co-founder of FitnessGenes, Ltd.