Energy cost of walking at a fixed pace and self-paced before, during and after pregnancy

Article Abstract:

The amount of energy expended while performing various activities has been measured in pregnant women. Because they must move a heavier body as pregnancy progresses, it was expected that they would burn more calories than nonpregnant women. But it was found that the energy expenditure of pregnant women was the same, or even lower, than that of nonpregnant women. This was explained by the tendency of pregnant women to move at a slower pace to compensate for the extra work of moving a heavier body. But researchers wondered whether energy expenditure would be higher in pregnancy if the woman was not able to reduce her pace. The energy expenditure of 39 healthy Dutch women was measured while walking at a fixed pace on a treadmill during and after pregnancy; they were not allowed to move more slowly as they gained weight during the later months of pregnancy. Fifteen of these women had been evaluated before pregnancy as well. Treadmill metabolic rate (energy expenditure, TMR) was higher in late pregnancy (36 weeks) than at 24 weeks gestation or 9 weeks postpartum. But it was considered remarkable that the TMR was constant throughout the first two trimesters of pregnancy and was also the same as before and after pregnancy, even though by the end of the second trimester the women had gained more than 13 pounds on average. The results clearly demonstrate that throughout most of pregnancy, energy expenditure during treadmill exercise is not directly dependent on body weight. The caloric cost of treadmill walking was actually two percent lower on average during pregnancy than before or after pregnancy; this was due to increased energy efficiency during pregnancy. The practical application of this information is that during the first and second trimester of pregnancy women who engage in substantial amounts of weight-bearing exercise do not need any more calories to support exercise than do nonpregnant women. A given activity at a set pace appears to use up the same amount of calories in a pregnant woman as in a nonpregnant woman. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Exercise, Aerobic exercises, Pregnancy

---

Energy metabolism of overweight women 1 mo and 1 y after an 8-wk slimming period

Article Abstract:

Research studies have clearly demonstrated that the amount of energy (calories) burned by the body decreases while on a low-calorie diet. There are several reasons for this: the amount of lean (muscle) tissue decreases, so less energy is needed to maintain its function; less food is consumed so the heat production that follows a meal is lower; less energy is expended to move the body because it weighs less; and metabolic adaptation may also occur. This last phenomenon was explored to determine whether metabolic adaptation, specifically a slowed metabolism, occurs during and then continues after a period of calorie restriction and weight loss. If the metabolic rate remains slowed after dieting, this could explain the tendency to easily regain the weight lost, a complaint of many dieters. A group of 13 overweight women was studied before and after eight weeks of dieting. Most the women were again evaluated one month and one year after the dieting period ended. The evaluations consisted of measuring their energy expenditure over 24 hours and monitoring their spontaneous physical activity. Each subject was individually evaluated in a respiration chamber, a sealed room in which the person's use of oxygen and production of carbon dioxide can be measured; these values are indicative of the energy burned. Results showed that the women lost an average of 20 pounds and kept the weight off throughout the follow-up period. During the entire study, no changes in energy requirement (based on body weight) or metabolic efficiency were noted. Spontaneous activity decreased while dieting and then increased afterwards. These findings support other studies, which have reported that no metabolic adaptations occur during, or persist after, short-term dieting. The possibility remains that individuals deprived of adequate calories throughout their lives adapt to this situation with a slowed metabolic rate. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Basal metabolism, Low-calorie diet, Low calorie diet

---

Adaptation of energy metabolism of overweight women to alternating and continuous low energy intake

Article Abstract:

Previous studies have reported that during fasting or prolonged dieting, the metabolic rate of individuals decreases by 6 to 30 percent. In subjects who lost weight, the amount of energy burned per day also dropped by 10 to 15 percent. A slimming diet has been used in the Netherlands were the dieter alternates between eating only bread and water on one day and eating normally the next day. Some believe this alternating approach is more effective in promoting weight loss than a continuous low-calorie diet because of metabolic rate effects. Twenty-seven overweight women participated in a study that compared the alternating pattern with continuous calorie restriction. The subjects followed three different reducing diets: a diet that alternated daily between bread and water and a weight maintenance regimen; a diet that continuously supplied 50 percent of weight maintenance needs; and a diet that alternated daily between 50 percent and 100 percent of weight maintenance needs. These different regimens were compared based on their effect on metabolic rate; this was obtained by measuring the amount of energy subjects expended while sleeping and energy expended over 24 hours. Alteration between low and maintenance caloric intake did not result in a decline of metabolic rate. After eight weeks of dieting with various combinations of regimens, subjects had a 7 to 13 percent reduction in sleeping energy expenditure and a 12 to 16 percent reduction in 24-hour energy expenditure. Subjects also spontaneously reduced their physical activity while dieting. The decline in energy expenditure was attributed to loss of body weight, reduced physical activity, and reduction in energy burned while digesting lesser amounts of food. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation

Similar abstracts:

• Abstracts: A preliminary report of prenatal cocaine exposure and respiratory distress syndrome in premature infants. Growth, Development, and Behavior in Early Childhood Following Prenatal Cocaine Exposure: A Systematic Review
• Abstracts: Pharmacokinetics and pharmacodynamics of ritodrine after intramuscular administration to pregnant women Pharmacokinetics of orally administered ritodrine
• Abstracts: n-3 Fatty acids of marine origin lower systolic blood pressure and triglycerides but raise LDL cholesterol compared with n-3 and n-6 fatty acids from plants
• Abstracts: Hospital use and mortality among Medicare beneficiaries in Boston and New Haven. Variations in rates of hospitalization of children in three urban communities
• Abstracts: The relation of aspirin use during the first trimester of pregnancy to congenital cardiac defects. Periconceptional folic acid exposure and risk of occurrent neural tube defects

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.