Maximizing the Benefits of GLP-1 Medications

GLP-1 Benefits and Body Composition

The most well-known GLP-1 clinical trials include STEP (Semaglutide Treatment Effect in People with Obesity) and SELECT (Semaglutide Effects on Cardiovascular Outcomes in People with Overweight or Obesity).

The STEP and SELECT clinical trials investigated the effects of semaglutide, a GLP-1 receptor agonist. A receptor agonist is a naturally occurring substance—like hormones or neurotransmitters—that your body produces to regulate various functions.

Receptor agonists can be medications designed to imitate natural substances and trigger desired effects—for example, pain relief or blood pressure regulation.

GLP-1 receptor agonists are medications that copy natural hormones. This medication acts as a helper for your body's natural system that controls blood sugar and fullness. It activates receptors in your body (GLP-1 receptors) that promote your pancreas to release more insulin when blood sugar levels are high—while slowing how quickly your stomach empties, making you feel fuller longer.

The GLP-1 clinical trials were studied for different intended uses and effects.

• STEP focused on the efficacy and safety of semaglutide for weight management in individuals with overweight or obesity (with and without type 2 diabetes).
• SELECT examined the impact of semaglutide on cardiovascular outcomes in individuals with overweight or obesity and established cardiovascular disease (CVD), but without diabetes.

While the average weight loss varied across different STEP trials and dosages, some trials like STEP UP and BioSpace (semaglutide 7.2 mg vs 2.4 mg) did show a significant percentage of participants achieving over 20% or even 25% weight loss, particularly at higher doses.

However, this represents the upper end of participants with an average weight loss of around 15% to 21% in various STEP trials for those without diabetes.

In some studies, a portion of total weight loss included a reduction in lean mass ranging between 40% and 60%. Other studies show lean mass reductions of approximately 15% or less of the total weight lost.

Current data also indicates that using GLP-1s for weight loss may accelerate age-related muscle and bone loss. This loss of lean mass is concerning, particularly for long-term health. The lack of lean muscle mass and bone density can lead to poorer health outcomes in an aging population.

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Lifestyle Modifications to Maximize GLP-1 Benefits

To get the most out of GLP-1 medications, it’s important to pair them with healthy habits. GLP-1s are a tool that works best when supported by balanced nutrition, regular movement, and mindful routines.

As a fitness and wellness professional, you’re positioned to help clients create simple, sustainable healthy habits that help them feel their best and maximize the benefits of their medication.

Nutrition

Weight loss from GLP-1 medications is primarily due to a large calorie deficit. This makes it increasingly important for fitness and wellness professionals to apply evidence-based strategies that support healthy eating patterns and promote nutrient dense foods.

It’s also important to consider dietary strategies that reduce the loss of lean body mass and bone density for clients using GLP-1s for weight loss.

• Create an appropriate calorie deficit. GLP-1 medications reduce appetite and may slow stomach emptying, making it easier to consume fewer calories. However, weight loss ultimately depends on consistently consuming fewer calories than the body burns (calorie deficit). Focus on a calorie deficit ranging from 250 to 750 kcals per day, depending on the individual.
• Increase protein intake. GLP-1 medications are highly effective in managing weight and blood sugar, but they can significantly reduce appetite, potentially leading to insufficient intake of crucial nutrients like protein. Protein intake should be moderate to high during caloric restriction—current evidence suggests 0.7 to 1.0 grams per pound for active adults during weight loss periods.
• Modify diet patterns with moderate carbohydrate intake. GLP-1 medications regulate blood sugar levels. A diet with moderate, complex carbohydrate intake prevents rapid spikes and crashes in blood sugar that may contradict the medication's effects. Aim for carbohydrate intake of 40% to 55% of total daily calories.

As fitness and wellness professionals, educating your clients and communicating evidence-based nutrition guidelines maximize their results while using GLP-1s for weight loss. It takes a clear understanding of methodology, support, and coaching with empathy for your clients to see positive, lasting change. Become a Certified Nutrition Coach and learn how to fuel their transformation and deliver nutrition as a foundation for long-term health.

Exercise

Exercise plays a crucial role in body composition results and maintaining bone density during weight loss. Data specific to GLP-1 trials is limited, but some studies suggest exercise reduces bone mineral density loss during weight loss with GLP-1 medication.

Resistance and aerobic training preserve lean body mass during caloric restriction.

Creating evidence-based exercise training plans for clients using GLP-1s for weight loss is within your scope of practice as a Certified Wellness Coach and Certified Personal Trainer.

Each client using GLP-1s for weight loss requires a unique approach, but some general exercise guidelines apply:

• Be mindful of low energy initially. Semaglutide, as a GLP-1 receptor agonist, regulates blood sugar, slows digestion, and reduces appetite by mimicking a hormone. These changes can lead to fatigue and nausea in some individuals during the initial phase as their bodies adjust. Fatigue or nausea can affect performance. Start with lower volume and build gradually.
• Include strategic cardio. The slowed digestion associated with GLP-1 medications makes it challenging to adequately fuel and rehydrate—hindering muscle repair and energy replenishment. Intense or prolonged cardio sessions—especially without adequate fueling and recovery—can increase fatigue and lengthen recovery times. Incorporate about three hours of moderate-intensity aerobic exercise (approximately 50% to 70% of VO2Max) weekly to support fat loss without compromising muscle. Avoid excessive cardio that could impair recovery.
• Prioritize resistance training. Strength training is crucial for preserving muscle mass, which can be particularly important during weight loss, including while using GLP-1s. Aim for two to four resistant training sessions per week. Focus on compound movements—moderate to heavy loads (50% to 80% of 1RM)—and progressive overload to stimulate muscle retention.

Behavior Change and Healthy Habits

Nutrition and exercise recommendations maximize the benefits of GLP-1 medications for clients, but only if they are rooted in behavior change and healthy habits.

Behavior change refers to the process of modifying actions, habits, or patterns of behavior. This includes understanding things that influence behavior and designing strategies to achieve desired results.

The Transtheoretical Model (TTM), also known as the Stages of Change model, was introduced in the late 1970s. The Stages of Change model is a framework that describes how people modify or adopt a new, healthy behavior. Specifically, this framework says change is a gradual process and happens in stages: pre-contemplation, contemplation, preparation, action, and maintenance.

But people don’t move through the stages of change easily or linearly. The resistance to change—while natural—comes from many sources. From fear of the unknown and emotional responses to established routines, all provide a sense of security.

Despite the proven success of the Stages of Change model, James O. Prochaska, PhD, and author of Changing to Thrive, said, “Most people fail when they attempt to change because they don’t know how to change.”

“Without expert guidance, a great number of people repeatedly fail to change behaviors that prevent them from living healthier and happier lives,” Prochaska said. “By the time people recognize unhealthy behaviors, they have become deep seated habits.”

James Clear, author of Atomic Habits, explained habit formation as a four-step process: cue, craving, response, and reward.

Referred to as the 1% better everyday principle, Clear suggested: “Instead of trying to overhaul your entire life at once, focus on making tiny improvements—over time, these lead to significant changes.”

Help clients put behavior changes into practice and reinforce healthy habits.

• Create positive reward loops. Building positive behaviors starts with intentional reward loops. For example, creating a reward system for consistent exercise reinforces these behaviors.
• Develop coping strategies. Stress is a major contributing factor for failing to meet goals. Mindful stress management helps identify and navigate stress with healthy coping strategies, relevant to your scope of practice.
• Encourage self-monitoring. Tracking body weight, food intake, physical activity, and subjective feelings reinforces behaviors and celebrates success.
• Set achievable goals. Using the SMART (Specific, Measurable, Achievable, Relevant, Time-bound) framework, create client goals that promote self-efficacy and trust in themselves for long-term behavior change.

Understanding the science of behavior change and habit formation helps your clients build healthy habits—maximizing the benefits of GLP-1 medications to create lasting change.

Callout: Master the key to success in creating authentic, long-lasting behavior change with NASM’s Certified Wellness Coach. Gain insights from world-class professionals in movement, psychology, nutrition, and recovery—transforming your approach to life and work, helping clients surpass their expectations and achieve ambitious goals.

Helping clients maximize GLP-1 benefits starts with Understanding Weight Loss Medications . NASM’s evidence-based content digs into scientific research, covers practical applications, and shares insights from industry experts. Gain the knowledge to safely and effectively guide clients using GLP-1s for weight loss, increase healthy habits, and improve their health and well-being.

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