Can hormones affect fat loss in men?

Trying to lose fat but not getting anywhere can be frustrating — especially if you’re exercising, eating well, and still seeing little change. 

While calorie balance still plays the biggest role, hormones can influence how easily you lose fat. They affect everything from how your body stores fat to your appetite, energy levels, and ability to build or maintain muscle. 

In men, testosterone often gets most of the attention, but insulin, cortisol, and thyroid hormones can all play a role. Research suggests this relationship is often two-way: excess body fat can disrupt hormones, and those hormonal changes can then make fat loss feel harder [1].

• How fat loss actually works (caloric balance explained)
• Which hormones affect fat loss in men?
• Signs your hormones may be affecting fat loss
• When should you consider a blood test?

How fat loss actually works (caloric balance explained)
 

The rules are simple. If you are in a calorie deficit (eating less than you burn), you will lose body fat. If you are in a calorie surplus (eating more than you burn), you will gain fat.

Your maintenance calories (the amount you need to stay the same weight) varies from person to person. They depend on factors like your size, activity level, age, and metabolism. 

Not all calories affect your body in the same way. Highly processed foods can make it easier to overeat, while whole foods tend to be more filling and nutrient-dense. 

So, where do hormones fit into this?

Hormones play a role in body composition and metabolism. This means that an imbalance can reduce your maintenance value, making it harder to lose fat. Hormones may also alter your eating habits by affecting your appetite and mood.

Which hormones affect fat loss in men?
 

Several hormones can influence how easily your body stores or burns fat, as well as your appetite, energy levels, and muscle mass.

In men, testosterone is often the main focus, but insulin, cortisol, and thyroid hormones can also play important roles.

1. Testosterone and fat loss

Testosterone is a male sex hormone that can significantly impact fat loss. Low testosterone can alter body composition by reducing lean muscle mass and increasing body fat [2]. It can also affect mood and energy levels, which may encourage unhealthier eating habits.

If you’re struggling to lose fat alongside symptoms like low libido or low energy, it may be worth checking your testosterone levels with a Testosterone Blood Test. This is especially true if you’ve struggled to lose weight despite following a diet and fitness regimen consistently, along with symptoms like having a low sex drive. 

Borderline low levels of testosterone are generally best treated with lifestyle changes. Find out how you can boost your testosterone levels naturally. 

In some cases, low testosterone is significant enough to warrant treatment with testosterone replacement therapy (TRT). If this is you, TRT is likely to make it easier to lose body fat, provided you live a healthy lifestyle alongside your treatment.

2. Cortisol weight gain

When you’re stressed, your body releases stress hormones like adrenaline and cortisol as part of the body’s fight or flight response. This is fine, at least in the short term, but it becomes a problem when you’re stressed all the time. 

Chronic stress has been linked to [3]:

• High blood pressure
• Insomnia
• Headaches and migraines
• Chronic inflammation
• Impaired immunity
• Cardiovascular disease
• Depression and anxiety

Cortisol can increase your appetite and cravings for high-calorie foods, which may lead to weight gain over time [4]. Cortisol also inhibits the effects of other hormones, which can lead to increased visceral fat (the ‘hidden fat’ stored around the organs) [5]. High levels of visceral fat increase your risk of type 2 diabetes and coronary heart disease. 

It’s therefore important to reduce stress where you can. There are many ways to combat stress, such as exercising regularly and incorporating stress-busting activities into your daily routine, like yoga or meditation. See our top ten ways to de-stress. 

You can measure your cortisol levels with a Cortisol Saliva Stress Tests or our at-home Cortisol Blood Test.

3. Insulin and fat storage

Insulin has several roles in the body. It helps to control blood sugar levels by stimulating tissues to absorb sugar from the bloodstream. Insulin also promotes fat storage. This can become an issue if you have a calorie surplus or in conditions like insulin resistance or diabetes. 

Being overweight or physically inactive increases your risk of insulin resistance and developing prediabetes or type 2 diabetes. As insulin becomes less effective, the pancreas tries to create more insulin to compensate, but it can eventually tire. One of the best ways to combat pre-diabetes or type 2 diabetes is to lose weight. This can be tricky, particularly as one of the side effects of diabetes medications, including insulin, is weight gain.

Check your blood sugar control with our Diabetes (HbA1c) Blood Test. This gives you an idea of your blood sugar levels over the last three months and can determine whether you may have prediabetes or diabetes.

4. Thyroid hormones and metabolism 

Thyroid hormones affect metabolism, so they can have a direct impact on your weight. Weight gain is common when the thyroid is not producing enough thyroxine (an underactive thyroid). This condition most commonly affects women over 50, but it can affect anyone at any age.

The good news is that treatment is often very effective with medications or surgery. If you’ve gained weight due to a thyroid problem, you’re likely to see improvements with treatment, if you lead a healthy lifestyle. 

If you’re worried you may have a thyroid condition, you can check your thyroid-stimulating hormone levels with our Thyroid Function Blood Test.

Signs your hormones may be affecting fat loss
 

Hormones cannot stop fat loss on their own, because calorie balance still has the final say. Diet and exercise will always be the biggest drivers. However, some hormone imbalances can make fat loss harder by affecting things like energy, appetite, sleep, body composition, and motivation.

Hormones may be worth investigating if fat loss feels unusually difficult despite consistent diet and exercise, especially alongside symptoms such as:

• Low libido
• Fatigue
• Poor sleep
• Low mood
• Strong cravings
• Weight gain around the abdomen 

These symptoms don’t always mean there’s a hormone problem, but testing can help rule out or identify potential causes.

The good news is that many of these issues can be treated, so if you are concerned, it may be worth considering a blood test or speaking to your GP.

When should you consider a blood test?
 

If you’re eating well, exercising consistently, and still struggling to lose fat, a blood test can help identify whether hormones are playing a role.

Depending on your symptoms, testing may include:

• Testosterone, if low libido, low energy, or reduced muscle mass are also part of the picture
• HbA1c (blood sugar), if insulin resistance or prediabetes could be contributing
• Cortisol, if stress, poor sleep, and fatigue are affecting recovery and appetite
• Thyroid markers, if metabolism or wider symptoms suggest thyroid function could be involved

So, do hormones affect fat loss in men?

Hormones can influence how easy or difficult it feels to lose fat, but they don’t override calorie balance. Diet and exercise remain the most important factors.

However, if you’re doing everything right and still struggling, hormones could be part of the picture. In that case, testing can help you better understand what’s going on and guide your next steps.

References

1. Mazza, E., Troiano, E., Ferro, Y., Lisso, F., Tosi, M., Turco, E., Pujia, R. and Montalcini, T. (2024) ‘Obesity, Dietary Patterns, and Hormonal Balance Modulation: Gender-Specific Impacts’, Nutrients, 16(11), p. 1629. (Accessed: 29 April 2026) 
2. Ng Tang Fui M, Prendergast LA, Dupuis P, Raval M, Strauss BJ, Zajac JD, Grossmann M. Effects of testosterone treatment on body fat and lean mass in obese men on a hypocaloric diet: a randomised controlled trial. BMC Med. 2016 Oct 7;14(1):153. doi: 10.1186/s12916-016-0700-9. PMID: 27716209; PMCID: PMC5054608.
3. Schneiderman N, Ironson G, Siegel SD. Stress and health: psychological, behavioral, and biological determinants. Annu Rev Clin Psychol. 2005;1:607-28. doi: 10.1146/annurev.clinpsy.1.102803.144141. PMID: 17716101; PMCID: PMC2568977. 
4. van der Valk ES, Savas M, van Rossum EFC. Stress and Obesity: Are There More Susceptible Individuals? Curr Obes Rep. 2018 Jun;7(2):193-203. doi: 10.1007/s13679-018-0306-y. PMID: 29663153; PMCID: PMC5958156.