Large differences in serum leptin levels between nonwesternized and westernized populations: the Kitava study

Area of Science:

• Human physiology
• Nutritional science
• Population health

Background:

• Serum leptin, a key adipokine, plays a crucial role in regulating appetite and energy balance.
• Cross-cultural comparisons of leptin levels can elucidate the impact of lifestyle and environmental factors on metabolic health.

Purpose of the Study:

• To compare serum leptin concentrations between a non-westernized population (Kitava) and a westernized population (Sweden).
• To identify determinants of serum leptin levels in these distinct populations.

Main Methods:

• A cross-sectional survey was conducted comparing 163 Kitavans and 224 Swedes.
• Fasting serum leptin levels were analyzed, along with body mass index (BMI), triceps skinfolds (TSF), and fasting serum insulin.

Main Results:

• Geometric mean serum leptin was substantially lower in Kitavan males (1.5 ng/mL) and females (4.0 ng/mL) compared to Swedish males (4.9 ng/mL) and females (13.8 ng/mL) (P < 0.0001).
• In Kitavans, serum leptin correlated positively with TSF and, in females, with BMI, aligning with predicted levels based on adiposity measures.
• Leptin was not related to fasting serum insulin in Kitavans, which was notably lower than in Swedes.

Conclusions:

• Lower serum leptin concentrations in Kitavans are likely associated with the absence of overweight and hyperinsulinaemia.
• Simple measures of adiposity, such as TSF and BMI, can effectively predict serum leptin levels at a population level.