Factors Influencing Carbohydrate Metabolism in Man

Effect of Protracted Intermittent Fasting on the Activities of Enzymes Involved in Energy Metabolism, and on the Concentrations of Glycogen, Protein and DNA in Skeletal Muscle of Obese Women

“…The glycogen levels in the obese women before fasting were lower compared with our controls (table II) and with control values reported in the literature (2,16,18). The recorded values approach those found in diabetic subjects (28).…”

“…The recorded values approach those found in diabetic subjects (28). Although the regulatory mechanism which controls the glycogen content of muscle is not fully known, the work of Hultman and Nilson (18), Roch-Norlund et al (28,29) and Bergstrom et al (2) emphasises the basic regulatory impor tance of insulin and glucose, the glycogen content being influenced also in a significant way by exercise and diet. With regard to this work, the lower glyco gen values we recorded in obese women could be associated with a lower biologi cal action of insulin in peripheral tissues (6,25), a problem which requires further investigation.…”

“…Hultman and Nihon (18) found after 7 days fasting at rest only slight and statistically insignificant changes in the glycogen content of skeletal muscle. They assumed that complete fasting will also have only a slight effect on the concentration of glycogen in skeletal muscle under conditions of rest.…”

Issues and Misconceptions About Obesity

“…They also spontaneously remain far below the level at which rapid conversion of carbohydrate into fat is induced in adults consuming mixed diets (12,13,34). Glycogen levels in adults can be estimated to vary between a lower limit of some 150-200 g and an upper limit of 500-600 g. Glycogen levels are known to be higher on high-carbohydrate than on low-carbohydrate diets (22). They are therefore not likely to vary over the entire range when conditions are stable, but to oscillate within a narrower range.…”

“…Carbohydrates generally contribute 40–60% of dietary energy and daily CHO intakes in adults consuming mixed diets range from 200 g in relatively small and sedentary individuals to >500 g in physically active persons. The body's glycogen reserves may be estimated to vary between 1.0 and 1.5 times the amount of carbohydrate consumed and oxidized during a typical day (22). The body's fat content commonly amounts to 10–15 kg, being much larger in obesity.…”