Decreased Skeletal Muscle Potassium in Obesity

The effect of body weight on total body potassium, skeletal muscle electrolytes and fat content was studied in seven lean and seven obese middle-aged men and seven lean and eight obese middle-aged women. Total body potassium and total body fat increased with body weight (p<0.01 and <0.05 for men, and p<0.05 and p<0.001 for women, respectively). So did muscle fat in men (p<0.01), while muscle tissue potassium was decreased in both obese men (p<0.001) and obese women (p<0.05). The skeletal muscle Na/K-ratio tended to be higher in obese men (p<0.1) but was not related to body weight in women. Skeletal muscle magnesium was higher (p<0.01) in obese men than in lean men. No differences between lean and obese women were found. Obese men had higher diastolic blood pressure (p<0.05) than lean men, while there was no difference between obese and lean women. Compared with lean subjects, obese subjects thus had lower relative skeletal muscle mass and men, especially, had more fat and less potassium in the skeletal muscle.