Appetite
Fat (adipose) tissue
Leptin
The "satiety" hormone that signals the brain that you have enough energy stored.
What it does
- Tells the brain you are full and can stop eating
- Regulates long-term energy balance
Too much
- Obesity often involves leptin resistance — high leptin but the brain stops responding
Too little
- Very low body fat lowers leptin, driving hunger and pausing reproduction
Keeping it balanced: Good sleep, avoiding ultra-processed food and steady weight support healthy leptin signalling.
Sources & references
Think a hormone may be out of balance?
The symptoms of hormonal excess and deficiency are non-specific — tiredness, weight change, low mood and poor sleep have many everyday causes. No hormone problem can be self-diagnosed from a symptom list.
Diagnosis needs blood tests interpreted alongside your history, sometimes repeated at set times of day because many hormones vary hour to hour. Speak to a GP if symptoms are persistent; seek urgent care for severe symptoms such as confusion, fainting, chest pain or extreme thirst with frequent urination.
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