The Endocrinology of Strongman: Hormones That Influence Mass, Strength and Recovery - Episode 7: Leptin, Ghrelin and Appetite Control

Episode 7: Leptin, Ghrelin and Appetite Control

Appetite is not simply a matter of willpower. It is the product of a network connecting the brain, adipose tissue, gastrointestinal tract, liver, pancreas, and endocrine systems with energy availability. For a Strongman athlete, this network becomes especially important: the athlete may need to sustain a large body mass and demanding training while sometimes also reducing body weight for a category or competition.

Leptin and ghrelin are two of the best-known signals in this network. Leptin communicates information about energy stores to the brain, while ghrelin is one of the major peripheral signals that stimulates hunger. Neither is a simple on-off switch. They work together with insulin, gut peptides, the melanocortin system, stress, sleep, and overall energy status.

1. Why the brain controls appetite

The hypothalamus is one of the main regions integrating information about energy and food. Neurons in the arcuate nucleus, together with other hypothalamic and brainstem regions, process information about energy stores, food intake, and the state of the organism.

2. Leptin: the signal of energy stores

Leptin is produced mainly by adipose tissue and, broadly speaking, circulates in proportion to fat mass. It acts on receptors in the brain and contributes to the regulation of food intake and energy expenditure.

The key concept is that leptin communicates information about adequacy of reserves. When energy stores fall, leptin can fall as well, and the brain receives a signal that favors energy conservation and greater motivation to eat.

3. Leptin is not simply a fat hormone

Leptin is part of an energy-defense system. It influences circuits that affect hunger, thermogenesis, the thyroid axis, and the reproductive axis. For that reason, falling leptin during energy restriction can have effects far beyond hunger itself.

4. Ghrelin: the hunger signal

Ghrelin is produced predominantly by the stomach and typically rises before meals, contributing to meal initiation. It acts on the brain and stimulates orexigenic circuits, including neurons expressing neuropeptide Y and agouti-related peptide.

In simple terms: ghrelin largely signals “it is time to seek energy,” while leptin contributes to the signal that “energy stores are sufficient.”

5. NPY/AgRP neurons and food drive

NPY/AgRP neurons in the hypothalamus are among the most important orexigenic circuits. When energy-deficit signals become strong, their activity can rise and stimulate food intake. In parallel, leptin and insulin tend to reduce this activity when energy is sufficient.

6. POMC and melanocortins: the appetite brake

Another major central circuit is formed by POMC neurons. Through melanocortin peptides, including α-MSH, this system reduces food intake and favors a less storage-oriented energy balance.

7. Leptin works through the balance of these circuits

Leptin does not control appetite through one neuron. It adjusts the balance between orexigenic pathways such as NPY/AgRP and anorexigenic pathways such as POMC. This is one reason the body's response to changes in body weight is so complex.

8. What happens when an athlete loses weight

As body weight and energy availability fall, leptin tends to fall and hunger signals can become stronger. At the same time, the body can reduce some components of energy expenditure and become more energy efficient.

This response is one reason weight loss becomes progressively harder. It is not only a matter of “eating less,” because the body actively tries to recover the energy that was lost.

9. Leptin and adaptation to energy restriction

During calorie restriction, leptin can fall faster than would be expected from the change in adipose tissue alone. This shows that the body responds to changes in energy availability, not just to the amount of stored fat.

10. Ghrelin during weight loss

Energy restriction and weight loss can alter ghrelin responses. For many people, hunger becomes harder to control as the deficit continues. In sport, this can make a long dieting phase more difficult than it looks on paper.

11. Leptin and thermogenesis

Leptin influences pathways involved in energy expenditure and thermogenesis. When leptin signaling falls, the body can favor energy conservation. This intersects with thyroid signaling and other systems discussed earlier in the series.

12. Thyroid, leptin and energy

As we saw in the thyroid episode, metabolism is not controlled by one hormone. Leptin can influence signaling that connects energy status with the hypothalamic-pituitary-thyroid axis. During energy restriction, changes in leptin and thyroid hormones may occur together as part of energy-conservation adaptations.

13. Ghrelin and growth hormone

Ghrelin also has a role in the growth hormone axis. It can stimulate GH secretion through mechanisms distinct from GHRH. This is another demonstration that food-related signals and growth signals are interconnected.

14. Hunger does not always mean nutrient deficiency

Hunger can occur before the body is truly lacking nutrients. It is an anticipatory and contextual signal. Meal timing, smell, food cues, routine, stress, and learned habits can all change appetite independently of immediate metabolic need.

15. Satiety matters just as much

The stomach and intestine send satiety signals through distension and hormones such as CCK, GLP-1, PYY, and oxyntomodulin. These signals combine with leptin and insulin to reduce the drive to keep eating.

16. Why a protein-rich meal can be very filling

Protein generally has an important satiating effect and can increase gut signals that reduce appetite. For a Strongman athlete in a calorie deficit, adequate protein can make hunger easier to manage without eliminating the hormonal responses to restriction.

17. Food volume and satiety

Foods with lower energy density can allow a larger food volume for the same calorie intake, which can help hunger control. However, a strength athlete still needs nutritional density, and carbohydrates and fats should not simply be removed to maximize food volume.

18. Sleep and appetite

Insufficient sleep can alter signals involved in hunger and satiety and can increase the drive to consume energy-dense foods. For a Strongman athlete, a poor night means not only worse recovery but also a more difficult nutrition strategy.

19. Stress and appetite

Stress can change appetite in either direction. Cortisol and reward circuits interact with hunger pathways, so some people eat more under stress while others lose their appetite.

20. Leptin resistance

In obesity, leptin concentration can be high while the central effect of the signal is reduced, a phenomenon described as leptin resistance. This explains why “more leptin in the blood” does not automatically mean “less hunger.”

21. Why leptin is not a weight-loss supplement

Increasing one hormonal signal artificially does not reproduce the complexity of weight-regulation physiology. Problems with sensitivity to energy signals can also limit the effect. Leptin has specific medical indications in rare forms of leptin deficiency; it is not a general solution for healthy athletes.

22. Ghrelin is not simply the “bad hormone”

Ghrelin has normal physiological functions, including roles in motility, GH secretion, and energy regulation. An athlete does not need to eliminate ghrelin, but to understand that hunger is normal biology and that energy restriction can amplify it.

23. What happens during an aggressive diet

The larger and more prolonged the deficit, the greater the chance of adaptations that make the diet harder to maintain: increased hunger, reduced energy expenditure, hormonal changes, and falling performance. In strength sport, the cost is not only psychological but also athletic.

24. Energy availability and performance

Insufficient energy availability can affect multiple endocrine systems and compromise recovery. Leptin is one of the signals that changes, but the picture also includes the reproductive axis, thyroid, GH/IGF-1, bone metabolism, and immune function.

25. Strongman and high energy requirements

A Strongman athlete can have very high energy expenditure, especially during high-volume phases, repeated-event training, and competition preparation. If intake does not keep up, hunger signals and energy-conservation adaptations can become pronounced.

26. Hunger can rise even when body weight stalls

One frustrating part of dieting is that appetite is not linearly related to the rate of weight loss. After a period of restriction, hunger can remain high even when the scale barely moves. Metabolic adaptation and changes in energy signaling contribute to this phenomenon.

27. Why regular meals can help

A predictable eating schedule can reduce the behavioral and contextual component of hunger without “resetting” hormones. For an athlete, meals synchronized with training can also help distribute energy and protein.

28. Leptin and weight maintenance

After weight loss, leptin often remains lower than before relative to the initial body weight, while hunger signals may remain stronger. This helps explain why weight regain is common after very restrictive diets.

29. Appetite control does not mean never feeling hungry

A good nutrition plan does not eliminate hunger completely. It makes hunger manageable, preserves enough energy for training, protects lean mass, and can be followed for long enough to work.

30. What a Strongman athlete should monitor

In practice, more important than measuring leptin or ghrelin are performance, body-weight trajectory, appetite, sleep, recovery, mood, training volume, and signs of low energy availability.

31. When appetite may indicate a problem

Persistent extreme hunger, rapid weight loss, falling performance, sleep disturbance, mood changes, or other symptoms can indicate an overly aggressive diet or a medical problem. In such situations, evaluation by a physician or dietitian is more useful than trying to manipulate one hormone.

32. Leptin, ghrelin and the rest of the series

Leptin and ghrelin complete the story started with testosterone, estrogen, cortisol, GH/IGF-1, and thyroid hormones. All of these systems respond to the same fundamental problem: how can the body remain functional while performance demands increase?

33. Conclusion

Leptin, ghrelin, and the central appetite-control network are essential for maintaining energy balance. Leptin provides information about the adequacy of energy stores, ghrelin stimulates hunger, and gut and neural signals turn each meal into a complex response of satiety or continued eating.

For Strongman, the lesson is simple but important: appetite should not be treated as an enemy or as a problem of willpower. It is a powerful biological function. The more aggressive the energy deficit and the poorer the recovery, the more strongly this network can push toward hunger and energy conservation. Long-term performance depends on managing the system, not winning a fight against one hormone.

Selected bibliography

1. Friedman JM, Halaas JL. “Leptin and the regulation of body weight in mammals.” Nature. 1998;395:763-770. DOI: 10.1038/27376.

2. Müller MJ, Geisler C. “Assessment of metabolic adaptations to weight loss.” Clinical Nutrition and related literature on energy expenditure and appetite adaptation.

3. Cummings DE, Purnell JQ, Frayo RS, et al. “A preprandial rise in plasma ghrelin levels suggests a role in meal initiation in humans.” Diabetes. 2001;50:1714-1719. DOI: 10.2337/diabetes.50.8.1714.

4. Morton GJ, Meek TH, Schwartz MW. “Neurobiology of food intake in health and disease.” Nature Reviews Neuroscience. 2014;15:367-378. DOI: 10.1038/nrn3745.

5. Speakman JR, Hards L, Jebb SA. Literature on the biology of appetite and weight-regain after weight loss.

6. Rosenbaum M, Leibel RL. “Adaptive thermogenesis in humans.” International Journal of Obesity. 2010;34 Suppl 1:S47-S55. DOI: 10.1038/ijo.2010.184.

7. Jeppesen JS, Hellsten Y, Melin A, Hansen M. “Short-Term Severe Low Energy Availability in Athletes: Molecular Mechanisms, Endocrine Responses, and Performance Outcomes—A Narrative Review.” Scandinavian Journal of Medicine & Science in Sports. 2025;35(6):e70089. DOI: 10.1111/sms.70089.

8. Recent review literature on leptin resistance, ghrelin signaling, GLP-1/PYY pathways, and appetite regulation in obesity and athletic energy balance.

9. Literature on the neuroendocrine response to low energy availability, including reproductive, thyroid, GH/IGF-1, bone, and immune systems.

10. Contemporary sports-nutrition literature on appetite regulation, weight-making, and energy availability in athletes.