Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist licensed in the UK for type 2 diabetes and weight management in adults with obesity or overweight with comorbidities. Whilst the medication offers substantial metabolic benefits, approximately 25% of weight lost may comprise lean muscle mass. Combining Mounjaro with strength training helps preserve muscle tissue, maintain metabolic rate, and optimise long-term outcomes. This article explores evidence-based strategies for safely integrating resistance exercise with tirzepatide treatment, addressing nutrition, energy management, and practical considerations for UK patients under NHS or private care.

Understanding Mounjaro (Tirzepatide) and Its Effects on Body Composition

Mounjaro (tirzepatide) is a prescription medicine licensed in the UK for the treatment of type 2 diabetes mellitus and, more recently, for weight management in adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) with at least one weight-related comorbidity. NHS access is governed by NICE guidance, which specifies eligibility criteria including previous engagement with lifestyle interventions.

As a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist, tirzepatide works through multiple mechanisms to improve glycaemic control and promote weight loss.

The medication enhances insulin secretion in a glucose-dependent manner, suppresses glucagon release, slows gastric emptying, and reduces appetite through central nervous system pathways. These combined effects typically result in significant weight reduction—clinical trials such as SURMOUNT-1 have demonstrated average weight losses of 15–20% of initial body weight over 72 weeks at higher doses (10-15mg) in populations primarily without diabetes. However, this weight loss comprises both fat mass and lean muscle mass, which raises important considerations for patients undertaking treatment.

Body composition changes during Mounjaro treatment warrant careful attention. Research indicates that approximately 25% of weight lost during pharmacological weight management may come from lean tissue, including skeletal muscle, although fat mass typically decreases proportionally more. This loss of muscle mass can affect metabolic rate, physical function, and long-term weight maintenance. The reduction in lean mass occurs due to the caloric deficit created by reduced appetite and the body's natural response to rapid weight loss.

Understanding these physiological changes is essential for patients and healthcare professionals alike. Whilst Mounjaro offers substantial benefits for weight management and metabolic health, preserving muscle mass through targeted interventions—particularly resistance exercise—becomes a critical component of comprehensive treatment planning. This approach helps maintain functional capacity, supports metabolic health, and optimises long-term outcomes.

Important safety considerations include: Mounjaro is not for use in type 1 diabetes; seek urgent medical help for severe abdominal pain (which may indicate pancreatitis or gallbladder disease), persistent vomiting or signs of dehydration; and avoid use during pregnancy and breastfeeding.

The Importance of Strength Training When Taking Mounjaro

Strength training, also known as resistance training, becomes particularly crucial during Mounjaro treatment to counteract the natural loss of lean muscle mass that accompanies significant weight reduction. Engaging in regular resistance exercise provides multiple physiological benefits that complement the medication's effects whilst mitigating potential drawbacks.

Resistance training stimulates muscle protein synthesis and creates an anabolic environment that helps preserve existing muscle tissue during caloric restriction. Studies examining weight loss interventions consistently demonstrate that individuals who incorporate strength training lose proportionally more fat and retain more lean mass compared to those relying on diet or medication alone. This preservation of muscle tissue is vital for maintaining resting metabolic rate—the number of calories your body burns at rest—which can otherwise decline substantially during weight loss and contribute to weight regain.

Beyond body composition, strength training offers additional advantages for individuals taking Mounjaro:

• Improved insulin sensitivity: Resistance exercise enhances glucose uptake in skeletal muscle, complementing Mounjaro's glycaemic effects

• Enhanced functional capacity: Maintaining strength supports daily activities, mobility, and independence

• Bone health protection: Weight-bearing exercise helps preserve bone mineral density, which may decline during rapid weight loss

• Cardiovascular benefits: Resistance training contributes to improved blood pressure, lipid profiles, and overall cardiovascular health

For patients with type 2 diabetes, the combination of Mounjaro and strength training may provide synergistic benefits for glycaemic control. The MHRA-approved prescribing information for tirzepatide specifically recommends lifestyle modifications, including physical activity, as part of comprehensive diabetes and weight management.

Current guidance from NICE emphasises that pharmacological weight management should always be accompanied by behavioural interventions, including increased physical activity. The UK Chief Medical Officers' Physical Activity Guidelines recommend muscle-strengthening activities on at least two days per week. Strength training represents a cornerstone of this approach, offering protection against muscle loss whilst enhancing the overall effectiveness of treatment.

If you have diabetes-related complications, seek specific advice: those with active retinopathy should avoid heavy straining or Valsalva manoeuvres, while people with peripheral neuropathy or foot ulcers need appropriate protective footwear and regular foot checks when exercising.

How to Safely Combine Mounjaro with Strength Training

Integrating strength training into your routine whilst taking Mounjaro requires a thoughtful, gradual approach that accounts for the medication's side effects and your individual fitness level. Safety and sustainability should guide your exercise planning, particularly during the initial months of treatment when gastrointestinal symptoms may be most pronounced.

Starting your strength training programme:

If you're new to resistance exercise, begin with bodyweight movements or light resistance bands before progressing to weights. Foundational exercises include squats, lunges, press-ups (modified as needed), and planks. Aim for 2–3 sessions per week initially, allowing at least 48 hours between sessions targeting the same muscle groups for adequate recovery. Each session might last 20–30 minutes as you build tolerance and technique.

For those with existing training experience, you may continue your established routine but monitor how Mounjaro affects your energy levels and recovery capacity. Some individuals report reduced exercise tolerance during the first weeks of treatment, necessitating temporary modifications to volume or intensity.

Managing common side effects during exercise:

Mounjaro frequently causes nausea, reduced appetite, and gastrointestinal discomfort, particularly following dose escalations. To minimise exercise-related issues:

• Time your workouts strategically: Exercise when you typically feel best, often mid-morning or early afternoon

• Stay well-hydrated: Aim for 6-8 drinks per day, increasing this with exercise and warm weather

• Avoid high-intensity training on difficult days: Listen to your body and opt for lighter sessions when experiencing significant side effects

• Consider exercise timing relative to meals: Some individuals tolerate exercise better on an empty stomach, whilst others prefer light pre-workout nutrition

When to seek medical advice:

Contact your GP or prescribing clinician if you experience persistent dizziness during exercise, unusual fatigue that doesn't improve with rest, or signs of hypoglycaemia (particularly if taking insulin or sulfonylureas, which may need dose adjustment). If you have pre-existing cardiovascular conditions, obtain medical clearance before commencing a new exercise programme.

Seek urgent medical help (call NHS 111 or 999 in emergencies) for severe, persistent abdominal pain (with or without vomiting), right-upper abdominal pain with fever, inability to keep fluids down, or reduced urination, as these may indicate serious conditions like pancreatitis, gallbladder disease, or dehydration leading to kidney problems.

If you have diabetes with foot problems or neuropathy, ensure you wear appropriate footwear and check your feet after exercise. Mounjaro should not be used during pregnancy or breastfeeding; discuss with your healthcare provider if you are planning pregnancy.

Optimising Nutrition and Protein Intake During Mounjaro Treatment

Adequate nutrition, particularly protein intake, becomes critically important when combining Mounjaro with strength training. The medication's appetite-suppressing effects can make meeting nutritional requirements challenging, yet proper nutrition is essential for muscle preservation, recovery, and overall health during weight loss.

Protein requirements during Mounjaro treatment:

Current evidence suggests that individuals undergoing significant weight loss whilst engaging in resistance training should consume approximately 1.2–1.6 grams of protein per kilogram of adjusted or target body weight daily. For someone with a target weight of 70 kg, this translates to 84–112 grams of protein daily. This elevated protein intake, distributed across meals, helps stimulate muscle protein synthesis and offset the catabolic effects of caloric restriction. If you have chronic kidney disease, discuss appropriate protein intake with your healthcare provider or dietitian.

High-quality protein sources include:

• Animal sources: Lean meats, poultry, fish, eggs, Greek yoghurt, cottage cheese

• Plant-based options: Legumes, tofu, tempeh, quinoa, nuts, seeds

• Supplemental protein: Whey or plant-based protein powders can help meet targets when appetite is suppressed (note carbohydrate content if you have diabetes)

Practical strategies for meeting nutritional needs:

Given Mounjaro's effects on appetite and gastric emptying, many patients find traditional meal patterns challenging. Consider these approaches:

• Prioritise protein at each eating occasion: Consume protein-rich foods first when appetite is present

• Opt for smaller, frequent meals: 4–6 smaller eating occasions may be better tolerated than three large meals

• Choose nutrient-dense foods: Focus on foods providing maximum nutrition per volume, such as eggs, Greek yoghurt, nut butters, and lean proteins

• Utilise liquid nutrition when appropriate: Protein smoothies or shakes can be easier to consume when solid food feels unappealing

Micronutrient considerations:

Rapid weight loss and reduced food intake increase the risk of micronutrient deficiencies. Ensure adequate intake of calcium, vitamin D (the NHS recommends 10 micrograms daily for many adults, particularly in autumn and winter), iron, and B vitamins. A comprehensive multivitamin may be advisable, though discuss this with your healthcare provider. Regular monitoring through blood tests, as recommended by your GP or specialist, helps identify any deficiencies requiring targeted supplementation.

Hydration remains paramount, particularly as Mounjaro can cause gastrointestinal fluid losses. Follow NHS guidance of 6-8 drinks daily, increasing this with exercise and warm weather.

Managing Energy Levels and Exercise Performance on Mounjaro

Many individuals taking Mounjaro report changes in energy levels and exercise performance, particularly during the initial months of treatment and following dose escalations. Understanding these effects and implementing appropriate strategies can help maintain training consistency and motivation throughout your treatment journey.

Common energy-related experiences:

The substantial caloric deficit created by Mounjaro, combined with its effects on slowing gastric emptying, can temporarily reduce exercise capacity. Patients frequently report feeling fatigued more quickly during workouts, experiencing longer recovery times between sessions, and noticing decreased strength or endurance compared to pre-treatment levels. These effects vary between individuals but are often most noticeable during the initial adaptation period.

Strategies for maintaining training quality:

• Adjust expectations realistically: Accept that some temporary reduction in performance is normal and doesn't indicate treatment failure

• Focus on consistency over intensity: Maintaining regular training frequency, even at reduced intensity, provides greater long-term benefits than sporadic high-intensity sessions

• Implement strategic deload weeks: Every 4–6 weeks, reduce training volume by 40–50% to facilitate recovery

• Monitor and record your sessions: Tracking workouts helps identify patterns and ensures progressive overload over time, even if progress is slower than pre-treatment

Optimising pre-workout nutrition:

Whilst appetite may be suppressed, consuming some easily digestible carbohydrates 1–2 hours before training can improve performance. Options include a banana, rice cakes with honey, or a small portion of oats. Experiment to find what your digestive system tolerates best whilst taking Mounjaro.

Recovery considerations:

Adequate sleep becomes even more critical during Mounjaro treatment. Aim for 7–9 hours nightly, as sleep deprivation impairs muscle recovery and can worsen fatigue. Additionally, consider incorporating active recovery activities such as walking, gentle yoga, or swimming on non-training days to promote circulation without excessive stress.

When energy concerns warrant medical review:

Whilst some fatigue is expected, persistent exhaustion that interferes with daily activities, doesn't improve over time, or is accompanied by other symptoms (dizziness, palpitations, breathlessness) should prompt consultation with your GP. Severe, persistent abdominal pain, vomiting, inability to keep fluids down, or reduced urination require urgent medical attention via NHS 111 or 999 in emergencies. These could indicate serious issues such as pancreatitis, gallbladder disease, dehydration leading to kidney problems, anaemia, or thyroid dysfunction. Your healthcare provider can assess whether adjustments to your Mounjaro dose, nutritional support, or additional investigations are needed.

If you experience any suspected side effects from Mounjaro, report them via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk or the Yellow Card app).

Frequently Asked Questions