From the Guidelines
Increased leptin levels are primarily caused by higher fat mass, as leptin is produced predominantly in adipocytes, and also by acute infection, mainly due to the action of inflammatory cytokines such as LPS, TNF, IL-6, and IL-1ß, as seen in studies 1. When considering the factors that influence leptin levels, it's essential to understand the role of leptin in energy homeostasis and its relationship with fat mass.
- Leptin is a satiety factor that regulates food intake and body mass, and its levels are higher with higher fat mass, theoretically acting as a regulator to decrease appetite in the presence of excess body weight and to increase energy expenditure, as noted in 1.
- However, most obese humans have high circulating levels of leptin due to leptin resistance, a lack of appropriate diminishing of appetite or decrease in fat mass despite relatively high leptin levels, as discussed in 1.
- Acute infection also induces leptin production, mainly through the action of inflammatory cytokines, which can lead to increased leptin levels, as seen in 1.
- The relationship between leptin and inflammatory factors is complex, and a better understanding of this relationship is needed, especially in the context of cardiovascular disease risk factors in children, as mentioned in 1.
- It's also important to note that leptin plays a crucial role in regulating immune responses, with effects on both myeloid and lymphoid cells, and its deficiency can lead to impaired immune function, as highlighted in 1.
From the Research
Factors Influencing Leptin Levels
- Leptin is a hormone that plays a crucial role in regulating body weight and energy balance 2, 3, 4
- Leptin levels are increased in obese individuals and are positively correlated with body mass index (BMI) 3, 5
- Insulin and glucocorticoids can upregulate leptin production in human adipose tissue, contributing to increased leptin levels in obesity 4
- Fasting can lead to a decline in serum leptin levels, while meal-induced increases in serum leptin are likely due to the effects of insulin and cortisol 3, 4
- Leptin levels can also be influenced by other factors, such as pituitary-adrenal activity, with an inverse correlation between leptin levels and cortisol levels observed in some studies 3
Dietary and Pharmacological Interventions
- A low-calorie diet can lead to a decrease in serum leptin levels, while an isocaloric diet with orlistat can cause an increase in serum adiponectin concentration and a decrease in serum leptin level 6
- Metformin therapy has been shown to decrease serum leptin levels in some studies, although the effects may vary depending on the specific population and intervention 6, 5
- The relationship between leptin levels and glycemia is complex, with some studies suggesting that leptin levels increase with disease duration in patients with type 2 diabetes mellitus and metabolic syndrome 5
Correlations and Associations
- Leptin levels are positively correlated with insulin levels and negatively correlated with pituitary-adrenal activity 3
- Leptin resistance is associated with insulin resistance, and there is a direct correlation between the two 5
- Changes in leptin levels are correlated with changes in body weight, BMI, and body composition, with the strongest correlations observed in response to orlistat treatment 6