The Rise of GLP-1: Threatening the Role of Nutritionists?

Bottom line

• Glucagon-like peptide-1 (GLP-1) agonists are an appetite suppressant 
• Clinical trials show up to 15% weight loss
• Stopping the drug results in weight regain
• When guidance from nutrition professionals is added to the mix, outcomes can be even more promising and sustainable

From red carpets to Instagram stories, glucagon-like peptide-1 (GLP-1) agonists have ignited a fervour in the field of weight loss.

Initially developed for managing Type 2 diabetes, their efficacy in promoting significant weight reduction—up to 15%— has captured the attention of both medical professionals and investors alike.

Named by Science as the ‘Breakthrough of the Year’, GLP-1 agonists have emerged as potent contenders in the battle against obesity. And the increasing demand of GLP1 has led to a supply shortage fuelling both the buzz and stock prices.

Key players like Novo Nordisk’s Wegovy and Eli Lilly’s Mounjaro, are leading the billion dollar pharmaceutical race. In fact, Wall Street analysts predict that the market for GLP-1 drugs could soar to a staggering $100 billion within a decade.

Let’s take a closer look at Wegovy

Novo Nordisk Wegovy’s generic name is semaglutide. It is administered as a once weekly injection. In a pivotal trial, people taking it lost an unprecedented 15% of their body weight over about 16 months compared to lifestyle-only group who lost about 2.4% of their weight. This level of weight loss comes close to the performance of metabolic surgery (ranging from 15-30%), and is the first time that double-digit weight loss has been achieved by pharmacological measures. Moreover, nearly a third lost 20% of their body weight.

Many on the drug also describe a dampening of “food noise,” the relentless and distressing desire to keep eating that hinders the ability to follow nutrition plans.

As the spotlight shines brighter on these revolutionary drugs, questions arise about their potential to diminish the role of nutritionists.

Will GLP-1 render the expertise of nutrition professionals obsolete?

This question arose with the latest headline highlighting the stock plunge of Weight Watchers after the company announced Oprah Winfrey was leaving its Board of Directors. Winfrey has sat on the board since 2015, but recently revealed she uses GLP-1 weight loss drugs – and is quoted saying that having access to the medication 'feels like relief, like redemption, like a gift'.

Before we delve into this debate and uncover the nuances of GLP-1's impact on weight loss and its implications for the future of nutritional guidance – let’s take a look at the physiological mechanisms in play.

What is GLP-1?

GLP-1 is a hormone secreted by the intestines, which plays a pivotal role in appetite regulation. It acts as a natural appetite suppressant, signalling to your brain that you’ve had enough to eat, reducing hunger and promoting satiety. It accomplishes this by slowing down gastric emptying (the rate at which food leaves your stomach) and inhibiting food intake.

Beyond appetite, GLP-1 also helps regulate blood glucose levels by enhancing insulin secretion and reducing glucagon release. This action promotes glucose utilization and stability.

However, obese individuals often experience reduced postprandial GLP-1 (GLP-1 after a meal). Why?

Several factors come into play:

Impaired Secretion: The gut’s ability to release GLP-1 is compromised.

Insulin Resistance: Obesity and insulin resistance affect GLP-1 levels.

Inflammation: Chronic inflammation linked to obesity disrupts GLP-1 signaling.

Adaptive Changes: The body adapts to chronic overeating, altering GLP-1 dynamics.

So it's GLP-1 receptor agonists to the rescue. 'Agonist' being a molecule that can bind and activate a receptor - in this case, GLP-1 receptors. 

A once weekly injection of Wegovy semaglutide raises GLP-1 levels, sending signals to the brain that make you feel less inclined to eat (i.e., dampening ‘food noise’), and delaying gastric emptying, making you feel full for a longer duration. These effects lead to reduced food intake and weight loss.

What’s a Nutritionist to Do?

While GLP-1 drugs offer significant benefits for promoting weight loss, some nutritionists may perceive them as a potential threat to their livelihood. As these medications gain popularity, clients might rely more on pharmacological solutions rather than personalized dietary guidance, impacting the demand for nutritionist services. 

However, it’s crucial not to overlook the holistic approach that nutritionists emphasise for those taking GLP-1 for the following two reasons: 

1. Diet and certain foods significantly influence GLP-1 production. Nutritionists can stress the importance of balanced eating to optimize GLP-1 levels.
2. Sustainable results extend beyond the drug itself. Achieving healthgoals involves a combination of lifestyle adjustments, behavioral changes, and psychological support. Nutritionists guide clients toward lasting well-being, considering the whole person.

The latter is even more important given that two-thirds of participants experienced weight regain upon discontinuing semaglutide. While lifelong use seems necessary to sustain benefits, concerns arise due to a sticker price exceeding US$1000 a month, and the absence of long-term safety data.

Diet’s Role in GLP-1 Secretion

Understanding the different aspects that meals play in impacting GLP-1 secretion is important. 

Firstly, the macronutrient composition of the meal consumed has notable effects on GLP-1 levels. For instance, carbohydrates, especially complex ones like whole grains, can stimulate GLP-1 release, while protein-rich meals also enhance secretion of this hormone. Conversely, fatty meals may have a lesser effect on GLP-1 levels. As such the balance of macronutrients—carbohydrates, proteins, and fats—in a meal affects GLP-1 secretion. Meals with a balanced nutrient composition may optimize the response of GLP-1.

Secondly, phytochemicals found in plant-based foods can influence GLP-1 secretion. Examples of phytochemical-rich foods include berries, green tea, and cruciferous vegetables.

Additionally, the size of the meal matters, with larger meals tending to stimulate more GLP-1 release, whereas smaller, frequent meals may have a different impact on GLP-1 levels.

Overall, understanding these factors provides insight into how dietary choices can modulate GLP-1 secretion and potentially influence metabolic health.

Moreover, the relationship between insulin sensitivity and GLP-1 responses is crucial. It's been observed that insulin sensitivity directly influences GLP-1 secretion, suggesting that tailoring diets to enhance insulin sensitivity could potentially optimize GLP-1 secretion.  

The timeless relevance of the Healthy Eating Guidelines 

Understanding how dietary choices modulate GLP-1 secretion and potentially influence metabolic health reinforces our long-standing dietary guidelines for healthy eating focused on whole foods, low-glycemic index carbohydrates, high-fiber foods, healthy fats, and lean proteins. And, perhaps another fist pump for the Mediterranean diet rich in fruits, vegetables, nuts, seeds, and olive oil, which have been associated with improved insulin sensitivity.

Long-live the Nutritionist

It is also important to remind the public (and continue to market) that nutritionists play a pivotal role in promoting not only weight loss but also overall health and well-being through personalized dietary guidance, behavior modification, and lifestyle interventions. Their expertise extends beyond simply prescribing a list of foods to eat or avoid; rather, they take into account individual preferences, cultural considerations, and socioeconomic factors to develop sustainable, long-term strategies for healthy living.

If you are not already doing so, we recommend doubling down on understanding behaviour change and addressing emotional and psychological aspects of weight management.

In this evolving landscape, it's essential to recognize that GLP-1 agonists are not a one-size-fits-all solution. While these medications can be effective for many individuals, they may not address the root causes of obesity or provide comprehensive lifestyle guidance.

Rather than viewing GLP-1 agonists as a replacement for nutritional guidance, it may be more fruitful to consider them as complementary tools in the broader spectrum of obesity management.

Weight Watchers has certainly done so with their programme specifically designed for users of GLP-1 agonists. Their efforts focus on:

• Behaviour change strategies for lasting habits
• Prioritising nutritious foods to ensure optimal intake
• Preserving muscle through protein intake, activity and strength training

Are you working with patients using GLP-1 agonists? Or simply have additional questions on their use - let us know here.

Check out fni.health podcast chat where we discuss efficacy and safety risks.