Leptin: Its Role in Obesity

Scientists are constantly looking to explain the overweight and obesity problem in the United States and leptin could be the answer. This hormone was first discovered in 1994 and was found to have a connection to the incidence of obesity in mice and more importantly, humans(1).

While leptin left the spotlight for some time, research regarding its role in being very overweight is booming. Leptin can not only demystify the desire to eat, but it can explain other parts of our behavior as well!

What is Leptin?

Leptin is one of many hormones that affect the control of hunger. Fat tissue makes it in relation to fat deposits, and it has a calming effect on appetite. The more fat we have the more leptin we produce and the less hungry we are- in general.

Leptin influences appetite and behavior. When leptin is low, the body increases appetite and lowers physical activity to preserve energy-an adaptive response to starvation. Studies suggest that too low or high leptin levels push us towards high-calorie foods during teenage years (2). This is important as teenage years are a critical period for determining eating patterns for adulthood.

Leptin and Obesity

Past belief suggests that obesity relates to leptin deficiency. If there isn’t enough leptin to keep hunger under control, then the person is constantly hungry and overeats. This, however, is not the case. Most overweight and obese individuals actually have an extra amount of leptin in circulation suggest meant that the leptin pathway is being overloaded.

A 2003 issue of Circulation (a scientific journal) examined the effects of this leptin surplus on hunger and metabolism (3). Leptin deficiencies and surpluses behave similarly to type 1 and type 2 diabetes, according to the Circulation. With type 1 diabetes being defined by a deficiency in insulin (similar to leptin deficiency) and type 2 being defined by a resistance to insulin (similar to leptin resistance). With leptin resistance being more common than leptin deficiency. In the case of obese individuals, there’s a decreased sensitivity to leptin. Unfortunately, this causes satiety- the feeling of satisfaction or fullness in the body, to not be detected by the brain in spite of the presence of high energy and fat stores.

It Effects on Weight-loss

When we lose weight and fat stores the production of leptin decreases. This stimulates hunger and lowers activity levels to refill fat. Brain activity shows that when leptin falls and there is an increase in activity in areas involved in emotional and cognitive control of eating (4). This means that the body’s first response to weight-loss is to regain it, so how do we keep the weight off?

The best thing to do for keeping the weight off is to avoid extreme and limiting diets to lose weight. The more extreme the weight-loss plan the more the body will tempt high-calorie foods and reduce physical activity. It is better to slowly lose excess weight by eating healthier foods and increasing physical activity.

References-

1. Castracane, V. Daniel, and Michael C. Henson. “The Obese (Ob/Ob) Mouse and the Discovery of Leptin.” Leptin Endocrine Updates, pp. 1–9., doi:10.1007/978-0-387-31416-7_1.
2. Jastreboff, Ania M., et al. “Leptin Is Associated With Exaggerated Brain Reward and Emotion Responses to Food Images in Adolescent Obesity.” Diabetes Care, vol. 37, no. 11, 2014, pp. 3061–3068., doi:10.2337/dc14-0525.
3. Sader, Sawsan, et al. “Leptin.” Circulation, vol. 108, no. 6, 2003, pp. 644–646., doi:10.1161/01.cir.0000081427.01306.7d.
4. Sader, Sawsan, et al. “Leptin.” Circulation, vol. 108, no. 6, 2003, pp. 644–646., doi:10.1161/01.cir.0000081427.01306.7d.