The impact of GLP-1 agonists on nutritional intake and deficiencies

GLP-1 agonists have taken the world by storm and have been shown to have significant beneficial health outcomes. However all is not well on the nutritional front because of the severe reduction in appetite and increased levels of satiety these GLP-1s can cause. In this article we reflect and outline the latest on the impact of GLP-1 treatment on nutritional intake as well as how this leads to nutritional deficiencies in macro and micronutrients. We propose a personalized health approach that is based on the preferences, symptoms, capabilities and motivation levels of the individual in order to instill behavior change early in the treatment.

Written by Mariette Abrahams PhD MBA

Background

GLP-1 agonists are a class of drugs that are used for the management of Diabetes. However their effectiveness in weight loss have made them being coined the “magic weight loss pill” we have been waiting for.

The GLP-1 prescriptions have increased over 500% over the past 5 years with the US leading the pack with 70% of the market. However, recent consumer surveys have demonstrated that European consumer interest is high but accessibility remains a problem. In fact, Morgan Stanley estimates that by 2035 around 9% of the US population will be on the drug.

The drug leads to around weight loss of about 15-20% of original body weight, which is a combination of fat mass and lean mass.

For a good overview of GLP-1 in nutrition, read our previous blog

The Effect of GLP-1 agonists - what we know so far

• Side effects are common with around 40-70% of people experiencing them

• 10-30% of individuals on treatment experience digestive problems such as stomach cramps, constipation, diarrhoea and reflux

• Users experience a loss of lean mass between 20-40%

• Loss of appetite by around 39%, reduced craving, increased satiety and a loss of enjoyment of food

• Other side effects include Hair loss, Fatigue, dehydration as well as “Ozempic face”

• Despite it being coined the magic pill (there is no such thing), not everybody responds to the drug in the same way, with 1 in 4 reaching lower than significant (> 5%) weight loss, and 20-40% regain 1/3 of their weight back within 1 year if diet and behavior adjustments have not been made.

25% of individuals on treatment, do not lose a significant amount of weight     

What we didn’t know was the extent to which GLP- 1 treatment leads to nutritional status

It is well documented that individuals who are overweight and who are obese have micronutrient deficiencies such as Vitamin D. This means that individuals who are started on GLP-1 treatment may already be deficient or have sub-optimal nutrient levels.

As mentioned above, GLP-1 treatment leads to a reduction in dietary intake, which means that total nutrient intake is impacted. What we did not know because previous studies have not specifically looked at this population group, is to what extend is dietary intake affected. A recent study (Johnson et al 2025) set out to find the answer to this question. Using data from a 3-day food diary and dietary intake questionnaires, researchers were able to determine that nutritional intake of GLP-1 users was inadequate, with most individuals consuming nutrients below the daily recommended intakes for:

• Fat soluble vitamins A,D,E,K,

• Protein and carbohydrate

• Fe, Magnesium, Calcium, Choline, Potassium,

• Fiber

• As well as the recommended public health guidelines for the number of servings for fruit, vegetables, grains, or dairy

Participants recorded a high intake of total fat and saturated fat which was above the recommended intake indicating that they were possibly sacrificing carbohydrates for a higher fat intake.

 

Does inadequate nutrient intake lead to nutritional deficiencies?

What we also did not know before, is if and what the potential magnitude of a nutritional deficiency could be as a result of initiating GLP-1 treatment. Thankfully another research group recently published their retrospective study (Butsch et al 2025) based on over 461K patients who were prescribed GLP-1A agonists between 2017-2021.

What they found:

• 13% had deficiency within 6 months and over 22 % had nutritional deficiencies diagnosed within one-year of starting GLP-1RA treatment

• Vitamin D and iron deficiencies were most severe

• Vitamin A, C, B also Calcium, selenium, Zinc and other levels were low.

Of course there is a time lag between the two studies and completely different participants, however it does provide a good snapshot of how GLP-1 treatment leads to inadequate intake resulting in nutrition deficiencies in adults without prior nutritional deficiencies.

By 2035 around 9% of the US population will be on the drug - Morgan Stanley

What this means

• Individuals on GLP-1 treatment whether for metabolic health or weight loss are more nutritionally deficient than previously suspected

• What people may perceive as a normal side effect of the drug, such as extreme fatigue, may in fact be a nutritional deficiency that should be treated.

• People who see a dietitian are more likely to receive a nutritional diagnosis and treatment plan yet less than 8% of individuals are referred to an RD in first 6 months of treatment. The reason for this low referral rate was not clear in the paper.

• Individuals need behavioral support to change their behavior long term to ensure that when the drug dose is reduced, new habits are already strong.

   

 

Time for a personalized health approach the Qina way

We are in science beyond the point where we are still quibbling about whether obesity is a results of a calories in and calories out approach. We know there are complex biology at play and we need to consider providing better and more targeted approaches. A Personalized health & nutrition fits perfectly here.

• This means referral to experts (nutrition, exercise, psychology), biological data (genetics, microbiome, metabolic signature) as well as psychological data (Food noise, emotional eating, stress etc)

• Guide individuals to solutions that support their day-to day decision making in combo with the RD at a cost people can afford or subsidized. This means tailored recommendations for meal kits if cooking skills are low, recipes if interest trying new foods is high, online diaries to educate about food composition, personalized supplements based on symptoms, a chatbot for instant answers and the list goes on

• Behavior change should start before treatment, this could help set expectations of the nutritional impact of treatment so they know what to expect and also what to track and report to their healthcare practitioner. A complete personalized plan could be developed for before, during and after treatment that is personalized to preferences, values, beliefs, perspectives and motivations in order to increase engagement and adherence.

• We should also not underestimate the social and psychological impact these drugs have on long term food choices and behavior; however, the research in this area is particularly sparse.

So if you are considering going onto GLP-1 treatment or you are a company or brand innovating in this area, make sure to really design for health by optimizing nutrient density and considering the nutritional impact of GLP-1 treatment on small appetites. Contribute to the body of research so more people can be helped as the number of people going on the drug is only set to rise.

My name is Mariette Abrahams, CEO & Founder of Qina, entrepreneur, thought leader and researcher at the intersection of Food, Health, Technology and Society. For more news, insights and developments into the personalized health & nutrition industry , sign up to Qina here.

References:

1. W. Scott Butsch, Suela Sulo, Andrew T. Chang, Jeeyun A. Kim, Kirk W. Kerr, Dominique R. Williams, Refaat Hegazi, Thadchaigeni Panchalingam, Scott Goates, Steven B. Heymsfield, Nutritional deficiencies and muscle loss in adults with type 2 diabetes using GLP-1 receptor agonists: A retrospective observational study, Obesity Pillars, Volume 15, 2025, 100186, ISSN 2667- 3681, https://doi.org/10.1016/j.obpill.2025.100186

2. McGlasson T, Green L, Kreider R and Jones R (2025) Investigating nutrient intake during use of glucagon-like peptide-1 receptor agonist: a cross-sectional study. Front. Nutr. 12:1566498. doi: 10.3389/fnut.2025.1566498