Testogel (testosterone gel) can influence body weight, though the relationship is more nuanced than simple weight gain. Many men using testosterone replacement therapy experience changes in body composition—gaining lean muscle mass whilst losing fat—rather than accumulating excess adipose tissue. Whilst 'weight increased' is not listed as a common side effect in the Testogel Summary of Product Characteristics, fluid retention can occur and may contribute to weight changes. Individual responses vary considerably, with some men reporting modest weight increases, others weight loss, and many noticing stability on the scales despite improved body composition. Understanding these effects helps set realistic expectations and enables collaborative treatment optimisation with your healthcare team.

Can Testogel Cause Weight Gain?

Testogel (testosterone gel) can influence body weight, though the relationship is more complex than simple weight gain. Many men using testosterone replacement therapy (TRT) experience changes in body composition rather than straightforward increases on the scales. Clinical evidence suggests that testosterone therapy may lead to increased lean muscle mass and reduced fat mass, which can result in weight gain because muscle is denser than fat.

According to the Testogel Summary of Product Characteristics (SmPC), 'weight increased' is not listed as a common side effect. However, fluid retention (oedema) can occur with testosterone therapy and may contribute to weight changes. Individual responses vary considerably—some men report modest weight increases, whilst others notice weight loss or stability. The key factor is often the shift in body composition—gaining muscle whilst losing fat—rather than accumulation of excess adipose tissue.

It is important to distinguish between healthy weight changes associated with improved body composition and problematic weight gain from fluid retention or increased appetite. Testosterone therapy is indicated only for men with confirmed hypogonadism (low testosterone levels with associated symptoms), and when properly monitored, should support healthier metabolic function. If you are concerned about weight changes whilst using Testogel, this warrants discussion with your GP or endocrinologist, as it may reflect treatment response, dosing considerations, or other underlying factors requiring assessment.

Understanding how testosterone affects your body can help set realistic expectations and enable you to work collaboratively with your healthcare team to optimise treatment outcomes.

How Testosterone Replacement Therapy Affects Body Composition

Testosterone plays a fundamental role in regulating body composition through multiple physiological mechanisms. As an anabolic hormone, testosterone promotes protein synthesis in skeletal muscle, which may lead to increased muscle mass and strength. It also influences fat metabolism, particularly in visceral adipose tissue.

Systematic reviews and meta-analyses of randomised controlled trials suggest that men receiving testosterone replacement therapy may experience favourable changes in body composition, with increases in lean body mass and reductions in fat mass over 6–12 months. These changes can occur even without structured exercise programmes, though physical activity generally enhances the benefits. The magnitude of change varies considerably between individuals and depends on baseline testosterone levels, treatment duration, and lifestyle factors.

The metabolic effects may extend beyond simple muscle and fat changes. Testosterone therapy can influence insulin sensitivity and other metabolic parameters in some men. Men with hypogonadism often present with increased central adiposity and reduced muscle mass before treatment, so TRT may help restore a more physiologically normal body composition.

It is worth noting that these compositional changes may not always translate to weight loss on the scales. Because muscle tissue is approximately 18% denser than fat tissue, replacing fat with muscle can maintain or even increase total body weight whilst improving overall health markers. This is why waist circumference, body composition analysis, and how clothing fits often provide better indicators of progress than weight alone. NICE Clinical Knowledge Summaries (CKS) on testosterone deficiency emphasise monitoring symptoms, testosterone levels, haematocrit, and prostate-specific antigen (PSA) as part of comprehensive treatment assessment.

Common Side Effects of Testogel

Testogel, like all medications, can cause side effects, though not everyone experiences them. According to the Testogel SmPC and Patient Information Leaflet (PIL), the most frequently reported adverse effects relate to local skin reactions at the application site, including dryness, irritation, erythema (redness), or pruritus (itching). These are generally mild and transient.

Systemic side effects that may occur include:

• Polycythaemia (increased red blood cell production), which requires monitoring through regular full blood counts

• Mood changes, including increased aggression, irritability, or mood swings in some individuals

• Acne or oily skin, resulting from increased sebaceous gland activity

• Gynaecomastia (breast tissue enlargement), though this is relatively uncommon

• Sleep disturbances, including possible worsening of sleep apnoea in susceptible individuals

• Prostate effects, including benign prostatic hyperplasia symptoms or elevated PSA levels

• Suppression of spermatogenesis, which can affect fertility

Fluid retention (oedema) can occur with testosterone therapy, which may contribute to weight changes and, in some cases, exacerbate conditions such as heart failure or hypertension. The SmPC advises caution in men with severe cardiac, hepatic, or renal insufficiency. Testosterone replacement therapy should only be used in men with confirmed hypogonadism.

Regular monitoring is essential, as recommended by NICE CKS. Monitoring typically includes baseline and periodic assessments of serum testosterone levels, full blood count (particularly haematocrit and haemoglobin), and PSA (with digital rectal examination where clinically indicated). Other tests such as liver function and lipid profile may be considered on a case-by-case basis depending on individual risk factors.

Transfer of testosterone to others through skin contact represents an important safety consideration. Partners, children, and pregnant women should avoid contact with application sites. Allow the gel to dry completely (3–5 minutes), wash your hands after application, cover the application area with clothing, and wash the area before anticipated skin-to-skin contact. Avoid washing or swimming for several hours after application to ensure adequate absorption.

If you experience any side effects, including those not listed in the Patient Information Leaflet, you should report them via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or search for MHRA Yellow Card in the Google Play or Apple App Store.

Managing Weight Changes While Using Testogel

If you experience weight changes whilst using Testogel, several practical strategies can help you manage your body composition effectively. The foundation of healthy weight management remains consistent regardless of testosterone therapy: balanced nutrition and regular physical activity.

Resistance training may be particularly beneficial during TRT. Testosterone's anabolic effects on muscle tissue can be enhanced when combined with progressive strength training. Aim for at least two sessions weekly targeting major muscle groups. Cardiovascular exercise (150 minutes of moderate-intensity activity weekly, as recommended by the UK Chief Medical Officers' Physical Activity Guidelines) complements resistance training by supporting cardiovascular health and calorie expenditure.

Nutritional considerations include:

• Adequate protein intake to support muscle health—discuss appropriate levels with your GP or a registered dietitian, particularly if you have kidney disease or other health conditions

• Balanced diet following the NHS Eatwell Guide, with emphasis on whole foods, vegetables, fruits, and whole grains

• Monitoring portion sizes, as some men report increased appetite with testosterone therapy

• Staying well-hydrated, particularly important if experiencing any fluid retention

Regular self-monitoring provides valuable feedback. Rather than focusing solely on scale weight, track waist circumference, how clothing fits, strength progression, and overall energy levels. Progress photographs taken monthly can reveal body composition changes that scales miss.

Some men find that initial weight changes stabilise after several months as the body adjusts to restored testosterone levels. If weight gain appears excessive or is accompanied by significant fluid retention (swelling in ankles, breathlessness, or sudden unexplained weight increase), contact your GP promptly. This may indicate fluid retention requiring assessment or dose adjustment. Do not adjust your dose without medical advice.

Keeping a simple diary noting weight, exercise, diet, and how you feel can help identify patterns and facilitate productive discussions with your healthcare team about optimising your treatment.

When to Speak to Your GP About Testogel and Weight

Certain weight-related changes whilst using Testogel warrant prompt medical review. Understanding when to seek advice ensures both safety and treatment optimisation.

Contact your GP or endocrinologist if you experience:

• Sudden unexplained weight gain, particularly if accompanied by swelling

• Swelling in the ankles, legs, or abdomen, suggesting possible fluid accumulation

• Breathlessness or reduced exercise tolerance, particularly if accompanied by weight gain

• Significant unintentional weight loss that seems disproportionate or is accompanied by other concerning symptoms

• Changes in body composition that concern you, even if not medically urgent

Seek urgent medical attention (call 999 or go to A&E) if you experience:

• Severe breathlessness or chest pain

• Sudden severe swelling with difficulty breathing

• New confusion or severe symptoms

Your scheduled monitoring appointments provide ideal opportunities to discuss weight and body composition changes. NICE CKS recommends regular follow-up for men on testosterone therapy, typically at 3 months, 6 months, 12 months, and then annually. These appointments should include discussion of treatment response, side effects, and any concerns. Monitoring typically includes serum testosterone levels, full blood count (haematocrit and haemoglobin), and PSA.

Before your appointment, it can be helpful to:

• Track your weight weekly at the same time of day

• Note any other symptoms or changes you have observed

• Record your exercise habits and any dietary changes

• Measure your waist circumference monthly

• List specific questions or concerns

Your GP may arrange additional investigations if weight changes seem problematic. Dose adjustments may be considered if testosterone levels are too high or if side effects outweigh benefits. Never adjust your dose without medical advice.

Remember that testosterone replacement therapy aims to improve quality of life and metabolic health in men with confirmed hypogonadism. Open communication with your healthcare team ensures that treatment remains safe, effective, and aligned with your health goals. Weight changes, when properly understood and managed, often reflect positive therapeutic effects rather than concerning side effects.

Frequently Asked Questions