Always hungry? How to naturally unlock the ‘fullness hormone’ to help weight loss

Doctors say that weight training is essential for physical health, but it also unlocks a secret aid that can help you lose weight. There is a hormone in your body called leptin that plays a fundamental role in regulating appetite – and lifting weights can actually boost its effectiveness.

As fitness expert Fran del Águila explains, strength training has surged in popularity recently – not just because it builds muscle and bone density, but also because of its influence on metabolism, body composition and appetite control.

How lifting weights influences the ‘fullness hormone’ leptin

On a hormonal level, strength training triggers a series of adaptations that directly affect how the body manages hunger and satiety. This is largely thanks to its impact on a key player in the endocrine system: leptin.

Produced mainly in adipose (fat) tissue, leptin is vital for regulating energy balance. But how exactly does a gym session fit into this hormonal puzzle?

Leptin resistance: Why your brain might be ignoring signals that you’re ‘full’

Dr Ana Revuelta explains that leptin’s primary function is to signal to the brain (specifically the hypothalamus) that the body has sufficient energy stored as fat. Simply put, it tells the brain, “We have enough fuel; you don’t need to be hungry.”

In fact, Dr Revuelta notes that many cases of obesity are driven by leptin resistance. “This means the brain stops responding properly to that ‘stop’ signal,” she explains. Consequently, the appetite stays high, and losing weight becomes increasingly difficult.

Boosting leptin sensitivity through muscle building 

This is where strength training becomes a game-changer. Del Águila points out that strength workouts help improve leptin sensitivity. By building lean muscle mass and reducing excess body fat, the body becomes more receptive to leptin’s signals. The result? You feel fuller, sooner.

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“By incorporating strength training into our routine, we take a significant step towards more effective appetite control and a healthy weight,” says Dr Revuelta.

Essentially, with strength training we:

• Burn calories & build muscle, which improves sensitivity to insulin and leptin.
• Regulate cortisol, a hormone which is spiked by stress and causes inflammation and fat retention.
• Optimise testosterone: This further aids in muscle growth and satiety.

Combining nutrition and exercise for hormonal balance 

It isn’t just about the long-term changes, either. Dr Revuelta notes that “intense strength workouts can temporarily reduce the hunger hormone (ghrelin) while influencing leptin levels, promoting an immediate feeling of fullness.”

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She confirms that a holistic approach is best: “Combining a balanced breakfast with strength workouts and a focus on whole foods supports both appetite control and [an improved muscle-to-fat ratio].”

Fitness expert Del Águila, meanwhile, reminds us that consistency is key. Results don’t happen overnight, and your exercise programme must be paired with a nutrient-rich diet. 

He also emphasises the importance of having fun: “Exercise should be rewarding. Find the type of workout you genuinely enjoy so you can to turn it into a sustainable habit.”

Beyond appetite: Additional benefits of strength training

 Furthermore, Del Águila mentions other benefits of strength training, such as:

About the experts

• Fran del Águila is Technical Director at JG Fitness in Madrid.
• Dr Ana Revuelta Alonso is an aesthetic doctor, pharmacist and nutritionist.