The rapid uptake of GLP-1-based weight loss medications is beginning to reshape how consumers interact with food at a physiological and behavioural level. According to Mark Gilbert, nutritionist at PortionIQ, the impact extends well beyond simple calorie reduction.

Recent innovations, such as Tirzepatide, combine GLP-1 with GIP (glucose-dependent insulinotropic polypeptide), amplifying appetite suppression and metabolic effects. Gilbert notes that approximately one in eight UK adults have now tried a GLP-1 medication, although most use them for less than a year.

“The distinction between hunger and appetite becomes critical,” he explains. “Hunger – the physiological drive to eat – and appetite – the psychological desire for food – are both significantly reduced.”

This dual suppression is driving measurable changes in consumption patterns. For many users, adherence to calorie-restricted diets becomes easier. However, Gilbert warns that this shift is not inherently positive from a nutritional standpoint.

“In some cases, the desire to eat becomes so low that intake may fall to dangerously low levels. More commonly, people simply eat less of the same nutritionally poor foods that contributed to weight gain in the first place.”

Nutritional risks move into focus

While appetite suppression is the primary mechanism behind GLP-1 efficacy, it also introduces a set of nutritional challenges that are now gaining attention across the healthcare and food industries.

Protein deficiency and lean mass loss

One of the most significant risks is inadequate protein intake. Gilbert highlights that individuals on GLP-1 therapies often fail to meet protein requirements due to reduced meal frequency and portion size.

Evidence from studies on Ozempic and Wegovy indicates that up to 40% of weight loss may come from lean mass, including muscle and bone.

“This is substantially higher than what we would expect from a well-structured dietary programme,” Gilbert notes. “In contrast, structured diets can limit lean mass loss to below 20%, and in some cases under 10%.”

The implications for long-term health are significant. Muscle mass is closely linked to metabolic rate, physical function and longevity, making its preservation a critical factor in sustainable weight management.

Fibre and micronutrient gaps

Beyond protein, fibre intake is another area of concern. Even in the general population, fibre consumption falls below recommended levels. Appetite suppression exacerbates this issue further.

Micronutrient deficiencies also present a systemic challenge. Gilbert identifies several nutrients already under-consumed across the UK population, including: Vitamin D (with up to 95% below recommended intake); Vitamin E; Magnesium; Calcium; Iron; Folate and iodine

“These deficiencies are almost certain to worsen under calorie restriction unless individuals receive targeted nutritional guidance,” he says.

The practical reality of hitting nutritional targets
While recommended protein intake for GLP-1 users sits between 1.2–1.6g per kilogram of bodyweight, achieving this in practice is challenging.

Gilbert provides a practical example: a 12-stone individual requires approximately 106g of protein per day. With reduced appetite, this would need to be distributed across smaller meals—around 35g per serving.

“That equates to roughly 150g of chicken breast or five eggs per meal,” he explains. “Most users are unlikely to consume this volume, and many are unaware of the requirement altogether.”

Meal skipping further compounds the issue, creating a consistent gap between nutritional needs and actual intake.

A new category: nutrient-dense, low-volume foods

The rise of GLP-1s is creating a clear opportunity — and necessity — for innovation in food formulation. Products must now deliver high levels of nutrition in smaller portions, without compromising taste or convenience.

PortionIQ, developed by Cambridge Nutritional Foods, is positioned within this emerging category.

Designing for “maximum nourishment in minimal volume”

Gilbert explains that the product range was developed specifically to address the nutritional risks associated with appetite suppression.

“We focused on high-quality protein, increased fibre and a comprehensive micronutrient profile,” he says. “The aim is to replicate what a meticulously planned, nutrient-dense meal would provide — within a much smaller volume.”

The range includes shakes, soups, bites and electrolyte drinks, formats selected for their convenience and compatibility with reduced appetite.

“Ease of consumption is critical. Products must be digestible, palatable and practical within real-world routines.”

Science-led formulation meets real-world behaviour

A key differentiator for PortionIQ is its foundation in total diet replacement (TDR) and meal replacement product (MRP) science — categories governed by strict nutritional standards.

Gilbert emphasises the importance of translating controlled clinical efficacy into real-world effectiveness.

“There is a significant difference between what works in a study and what works in everyday life,” he says. “Consumers are dealing with busy schedules, inconsistent eating patterns and behavioural challenges.”

The company’s approach builds on decades of research, including work led by Dr Allen Howard at the University of Cambridge, which explored optimal dietary composition and metabolic outcomes.

This body of evidence supports not only weight loss, but also improvements in: blood pressure; cardiovascular risk; sleep apnoea; and inflammation.

Misconceptions persist in the GLP-1 narrative

Despite growing adoption, misconceptions around GLP-1 medications remain widespread.

One of the most common is the belief that reduced appetite eliminates the need for structured nutrition.

“Feeling less hungry does not reduce the body’s requirement for essential nutrients,” Gilbert stresses. “Protein, vitamins and minerals remain critical for energy, cognitive function and overall health.”

Another misconception is the expectation of rapid, effortless weight loss. In reality, GLP-1 therapies require careful dose titration to minimise side effects, and outcomes vary depending on adherence and nutritional support.

Weight management: quality over quantity

The emergence of GLP-1s is reinforcing a long-standing principle in nutrition: weight loss is not solely about eating less, but about eating correctly.

Gilbert highlights the role of macronutrient composition in metabolic response.

“Protein has a unique effect — it increases metabolic rate, reduces appetite and helps preserve lean mass,” he explains. “Calories from protein are not equivalent to calories from carbohydrates or fat in terms of physiological impact.”

This distinction is becoming increasingly relevant as consumers rely more heavily on pharmacological appetite control.

Industry implications: formulation, messaging and responsibility

For the food and beverage industry, GLP-1 adoption presents both challenges and opportunities.

Product development priorities

• Manufacturers must now consider:
• Higher protein density in smaller portions
• Enhanced micronutrient fortification
• Functional fibre inclusion
• Improved satiety-to-volume ratios.

This shift may accelerate innovation in meal replacements, functional foods and medical nutrition products.

Communication and consumer education

Gilbert also highlights a gap in nutritional guidance.

According to NHS and NICE recommendations, GLP-1 users should receive structured dietary support. However, this is often not implemented in practice.

“At best, some users receive written advice, which is frequently not followed,” he says.

This creates a responsibility for brands to provide clear, evidence-based guidance alongside their products.

The future of GLP-1 nutrition

Looking ahead, Gilbert expects continued growth in products tailored to GLP-1 users, alongside a proliferation of less substantiated claims.

“We are likely to see more foods and supplements designed to support users,” he says. “But also products claiming to increase GLP-1 levels naturally.”

He cautions that such claims may lack meaningful impact, given that pharmaceutical GLP-1 analogues remain active in the body far longer and at significantly higher levels than endogenous hormone production.

Long-term behavioural shifts

The long-term role of GLP-1s in weight management remains uncertain. While some users discontinue treatment, others may adopt cyclical usage or maintenance dosing strategies.

A key challenge is weight regain following cessation, which may drive ongoing reliance on these medications.

“Unless perceptions of safety change, these drugs are likely to remain a significant part of the weight management landscape,” Gilbert concludes.

A new nutritional paradigm

GLP-1 medications are not simply another diet trend — they represent a structural shift in how appetite, consumption and nutrition intersect.

For the food and beverage sector, this shift demands:

• Reformulation of products to deliver higher nutritional density
• Greater emphasis on protein and micronutrient adequacy
• Integration of science-led approaches into product development
• Clear, responsible consumer communication.

As appetite becomes pharmacologically regulated, the industry’s role in ensuring nutritional adequacy becomes more critical than ever.

The success of this transition will depend not only on innovation, but on the ability to align scientific evidence with real-world consumer behaviour — delivering solutions that are both effective and practical in a fundamentally altered dietary landscape.

Mark Gilbert

Credentials: B.A.Sc (Nutrition), RNutr, CISSN  

Mark is a nutritionist for PortionIQ and has been involved in nutrition and healthcare for over 30 years. He is a recognised nutritionist and has held multiple certifications in sports nutrition, exercise science and pharmaceuticals. He is also currently science officer for TDMR Europe. As a consultant, Mark has advised dozens of multi-national companies on product formulation/IP, regulatory affairs, corporate investment and marketing.