Want to know the answer to what drives your appetite? It may not be down to a lack of willpower – it could actually be your hormones. Hormones play a key role in regulating your mood and improving your sleep, but they also have a significant effect on your appetite and eating behaviour and can help you maintain a healthy body weight.
The key hormones involved in regulating your body’s appetite are ghrelin, which causes hunger pangs, and leptin, which tells your brain when you’ve eaten enough.
‘Hormones that affect your appetite are an extremely complicated area of research, involving so many different factors,’ says Dr Guyomar. Here, she shares how they work and the lifestyle factors that will help to keep them working in harmony.
Known as the ‘hunger hormone’, ghrelin stimulates your appetite by signalling to your brain it’s time to eat. As well as making you want to eat more food, it also promotes fat storage. Ghrelin is produced in the stomach with smaller amounts secreted by the brain, small intestine and pancreas.
‘Although ghrelin is known for its role in stimulating appetite, it’s also involved in regulating glucose and insulin, taste sensation, and sleep,’ says Dr Guyomar. Ghrelin also encourages and increases the release of growth hormone from the pituitary gland, which helps maintain your metabolism, breaks down body fat and builds up muscles.
Levels of ghrelin will naturally change significantly throughout the day, rising dramatically before a meal and then falling after eating. When your stomach is empty, ghrelin is released and travels through your bloodstream to the hypothalamus region of the brain, where it stimulates neurons to signal hunger.
Diets and fasting can also make your ghrelin levels rise. When we restrict calories and lose weight as a result, ghrelin levels increase significantly. One study found there was a 24% rise in ghrelin levels in participants on a six-month diet.
‘Levels of ghrelin in the blood increase during dieting or fasting and this could explain why it’s difficult to achieve long-term weight-loss results from these methods,’ Dr Guyomar says.
‘People who suffer from anorexia nervosa [an eating disorder where you feel a need to keep your weight as low as possible] also have higher levels of ghrelin.’
Leptin is produced by the body’s fat-storing cells and plays an important role in managing your appetite by signalling to the brain when you’re full. It also helps to regulate your body weight and metabolism.
‘Leptin has many other roles within the body, like regulating your reproductive system, and it has vast effects on the immune system,’ says Dr Guyomar.
The level of leptin in your bloodstream is directly proportional to the amount of body fat you have. When your body fat goes up, your leptin levels will rise. Similarly, when your body fat goes down, your leptin levels will fall.
‘People with a higher body mass index [BMI] and more body fat have an increase of leptin circulating in their blood,’ says Dr Guyomar.
But sometimes the brain doesn’t respond to even the highest levels of leptin. This is known as ‘leptin resistance’ and means that the brain never receives the message that the stomach is full and instead assumes it’s starving. This can result in a continuous cycle of eating more and gaining weight.
Do you often feel hungry after a meal? The balance of ghrelin and leptin is crucial for the body’s appetite to function normally. The hormones work in partnership with one another to help you eat the right amount – with ghrelin increasing your appetite and leptin helping you feel satisfied. When the balance of hormones is altered, your ability to eat when you’re hungry and stop when you’re full may be jeopardised.
‘A balance between ghrelin and leptin is essential in maintaining a healthy body weight,’ says Dr Guyomar. ‘An imbalance of ghrelin and leptin may lead to significant weight gain or loss.’ An imbalance of these hormones has also been associated with eating and mood disorders.
Other hormones that may affect your appetite include:
Often known as the stress hormone, cortisol is released when your body is under stress, which can increase appetite and cause you to overeat. One study found participants who were under stress ate more and craved sugary foods
This gut hormone is released from the pancreas after eating and can reduce appetite
The female sex hormones play essential roles in regulating appetite. Studies have found that progesterone and testosterone stimulate appetite, while oestrogen inhibits it.
These simple lifestyle changes can help you keep your appetite hormones in check and maintain a healthy weight.
Not getting enough sleep on a regular basis can lower leptin levels and elevate ghrelin levels, increasing your appetite. Try and get at least 7-8 hours of sleep daily.
Always hungry after breakfast? A high-protein diet may leave you feeling fuller for longer and control your hunger.
Drastic weight changes and crash diets can disrupt your key appetite hormones. Dieters who have lost weight tend to have higher ghrelin levels, so are more likely to return to their old eating habits and gain weight after dieting. A balanced diet can help you maintain a healthy weight and balance your hormones.
It’s no secret that eating slowly may help you feel full faster, but it may also improve your appetite hormone responses. By slowing down and taking the time to enjoy food, you’re less likely to eat more than you need.
Not only can physical activity help maintain a healthy weight and reduce leptin resistance, but it can also reduce your risk of major illnesses, such as type 2 diabetes, heart disease and strokes. Incorporate more movement and exercise into your daily life with activities like cycling or walking.
This article has been medically reviewed by Dr Céline Guyomar, a Livi medical doctor.