Question: How does leptin impact appetite?
Answer: Leptin is a hormone produced by adipose tissue and is also known as the ‘satiety hormone’. Leptin acts on cells in the hypothalamus to inhibit hunger and works alongside Ghrelin, the ‘hunger hormone’ in regulating your energy balance. i.e. after a meal ghrelin levels decrease to limit hunger and leptin levels increase to create a feeling of satiety and limit overeating. The opposite occurs when you have digested your food and need to look for your next meal.
When a client loses weight and decreases fat mass stores, leptin levels fall which initiates a cascade of compensatory mechanisms such as appetite stimulation to increase food intake and stimulation of the parasympathetic nervous system which decreases core body temperature and basal metabolic rate. Conversely when fat mass is gained, leptin levels rise prompting a decrease in appetite and an increase in sympathetic nervous activity to increase body temperature and metabolic rate.
So, how do you explain the confounding situation of people who have excessive fat mass and still cannot control their appetite and lose weight? In clients with excessive fat stores, the phenomenon of ‘leptin resistance’ occurs. This is when there is decreased sensitivity to leptin due to chronically high levels, resulting in an inability to detect satiety despite high energy stores. Therefore, the signals to stop eating and the body’s natural responses to achieve energy homeostasis are nullified.
Even if a client has leptin resistance, studies suggest that there are things that can be done to help. For example ensuring adequate sleep each night can have a significant impact on leptin levels. Do you need to recommend that they go to bed earlier? Or be tested for sleep apnoea?
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