GLP-1 receptor agonists (GLP-1ra) are increasingly being used in the management of type 2 diabetes (T2DM) and obesity. Their effectiveness is well documented: by suppressing appetite, slowing gastric emptying and increasing satiety signalling, they help reduce food intake and support weight loss.

But while the conversation around GLP-1s often focuses on weight loss itself, far less attention is being paid to what can happen nutritionally when appetite is significantly reduced, particularly for women.

Because while energy intake may decrease during weight loss, the body’s physiological need for nutrients does not. In some cases, it may even increase. Your body doesn’t suddenly require less protein, fewer vitamins or fewer minerals simply because you’re eating less.

And this is where a growing area of concern is emerging.

A recent 2025 study published in ‘Frontiers in Nutrition’ explored nutrient intake in individuals using GLP-1 receptor agonists and found a clear pattern: reduced appetite was often accompanied by reduced dietary quality, lower protein intake and widespread micronutrient shortfalls (Johnson et al., 2025).

The issue isn’t necessarily the medication itself. It’s the fact that nutritional adequacy is often not being actively supported alongside it.

Why This Matters More for Women

Although reduced food intake affects both men and women, women may be particularly vulnerable to the nutritional consequences of GLP-1 therapies due to a combination of biological, hormonal and nutritional factors.

Women typically begin with lower absolute skeletal muscle mass than men, meaning any loss of lean tissue represents a greater proportional impact on metabolic health and physical function. At the same time, women are already more likely to have marginal baseline intakes of nutrients such as Iron, Calcium, Vitamin D and total energy.

This creates a much narrower margin for nutritional adequacy before treatment has even begun.

Hormonal shifts can further amplify this risk. During perimenopause and menopause, declining oestrogen levels are associated with accelerated muscle loss, reduced anabolic responsiveness and changes in fat distribution. When this is combined with reduced dietary intake, it can create a compounding effect: lower intake, reduced muscle preservation and increased metabolic vulnerability.

In other words, GLP-1-induced appetite suppression does not exist in isolation. It interacts with an already shifting physiological landscape, making nutritional adequacy more important, not less, for women.

What the Research Found

The study used detailed three-day food records to assess dietary intake in individuals using GLP-1 medication against established Dietary Reference Intakes (DRIs).

The findings showed a consistent trend: reduced appetite was associated with reduced nutritional adequacy across multiple areas of the diet.

Participants frequently failed to meet recommended intake levels for several key food groups, including fruit, vegetables, grains and dairy. This suggests appetite suppression doesn’t simply reduce how much people eat, but also affects dietary structure and variety. Smaller portions, simplified meals and reduced meal frequency may all contribute to a narrower range of nutrients overall.

Micronutrient Intake

One of the study’s most notable findings was the widespread insufficiency of several essential micronutrients. Participants consumed inadequate levels of:

• Fibre
• Calcium
• Iron
• Magnesium
• Potassium
• Vitamins A, C, D, E and K
• Choline

These nutrients play important roles across the body, supporting everything from bone health and neuromuscular function to immune defence and cellular energy metabolism.

The concern is not necessarily a single deficiency, but rather a broader reduction in nutrient density across the diet.

Protein Intake & Lean Mass

Protein intake also emerged as a significant concern.

When assessed relative to body weight and physiological demand, intake levels were often inadequate to support lean mass preservation during weight loss. This matters because protein requirements increase during periods of energy restriction in order to maintain muscle protein synthesis and limit muscle breakdown.

The study therefore highlights a mismatch between intake and metabolic demand, increasing the risk of lean tissue loss, particularly in women and older adults.

Lack of Nutritional Support

Another key finding was the lack of structured nutritional guidance being provided alongside treatment. Despite evidence of reduced dietary quality and nutrient insufficiency, only a minority of participants had received support from a dietitian or structured dietary advice. This highlights a critical gap in care: appetite is being actively suppressed, but nutritional adequacy is often not being actively managed.

The Bigger Picture: Many Women Are Already Nutritionally Vulnerable

The significance of these findings becomes even more important when viewed alongside data from the UK National Diet and Nutrition Survey (NDNS).

The NDNS consistently shows that many people across the UK population already fall below recommended intake levels for key nutrients including fibre, vitamin D, magnesium and potassium. Women are also disproportionately affected by low iron intake and inadequate overall energy intake.

This means many individuals may begin GLP-1 therapy from a position of marginal nutritional adequacy rather than optimal nutritional status. So, when food intake decreases further, nutritional gaps are often widened rather than newly created.

A Physiological Cascade

When energy intake drops but physiological demands remain the same, the body must adapt. Protein requirements increase during energy restriction in order to preserve lean mass, while micronutrient needs remain essential for metabolic and enzymatic function. Hormonal changes may further increase tissue vulnerability.

Over time, insufficient intake may contribute to:

• Loss of skeletal muscle
• Reduced metabolic efficiency
• Impaired recovery
• Increased fatigue
• Reduced functional capacity

These changes are not always immediately visible, but they can accumulate gradually and have important implications for long-term health.

What This Means in Practice

GLP-1 therapies can offer significant benefits for individuals with obesity and type 2 diabetes. But weight loss is not nutritionally neutral, and eating less does not reduce the body’s requirement for essential nutrients.

Protein intake matters

Protein should be prioritised to help preserve lean mass during weight loss. Without sufficient protein intake, muscle loss becomes increasingly likely, particularly for women and older adults.

Nutrient density becomes more important

As food volume decreases, meals need to provide higher concentrations of essential nutrients. Smaller meals need to work harder nutritionally.

Dietary structure still matters

Even with reduced appetite, maintaining regular eating patterns can help support more consistent nutrient intake and reduce the risk of prolonged under-eating.

Health is about more than body weight

Monitoring physiological health should extend beyond the number on the scale. Energy levels, strength, recovery and dietary intake all provide important context.

Nutritional support is essential

The study highlights the need for more structured nutritional guidance alongside GLP-1 treatment pathways. Dietetic support may be critical in helping individuals achieve safe, sustainable and nutritionally adequate outcomes.

The Bottom Line

GLP-1 therapies represent an important advancement in metabolic health and obesity management. But, their benefits are optimised when paired with intentional nutritional strategies.

Real-world evidence suggests that lower energy intake is often accompanied by poorer dietary quality, inadequate protein intake and widespread micronutrient insufficiency, particularly in women who may already be nutritionally vulnerable before treatment begins. The goal should not simply be to eat less, but to maintain adequate nutritional intake within that reduction.

Because sustainable health is about more than weight loss alone, it’s about preserving lean mass, supporting metabolic function and ensuring the body still receives the nutrients it needs to thrive.