Energy expenditure at rest and during exercise in nonobese female cyclical dieters and in nondieting control subjects

Article Abstract:

It has been suggested that alternating periods or cycles of weight loss and weight gain cause the body to use energy from food more efficiently; another way to describe this is that the metabolism slows down. This may result in an increase in weight gain when dieting stops, or a decrease in the amount of weight lost during each successive dieting period. The efficiency of the body in using food for energy can be determined by measuring the resting energy expenditure (REE, the amount of energy required to maintain normal body functions while the body is at rest) or by measuring the amount of weight lost during repeated periods of dieting. It has been reported that the rate at which body weight is lost decreases as the number of weight gain and weight loss periods increases. This has been demonstrated for high school wrestlers, who go through periods of weight loss prior to wrestling matches to be able to compete in the lowest weight group. To determine if repeated periods of weight loss and weight gain increase the body's ability to use food more efficiently (reduce the REE), the REE and exercise energy expenditure (EEE, the amount of energy expended during exercise) were determined in 11 non-obese female dieters and in 12 non-dieting females (control subjects). During a one-year period, the dieters had four separate periods of dieting (eating less than 1,000 calories per day) that lasted for at least 7 to 10 days each. On average, the females in the diet group weighed 20 pounds more and had 5 percent more body fat than the females who did not diet. The results of this study indicate that alternating periods of dieting and weight gain increases the ability of the body to use food more efficiently during exercise, but not while the body is at rest, in non-obese dieting women. (Consumer Summary produced by Reliance Medical Information, Inc.)

Dieters

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Effects of a very-low-calorie diet and physical-training regimens on body composition and resting metabolic rate in obese females

Article Abstract:

Very-low-calorie diets (VLCDs) can be used to lose weight rapidly, but they can be dangerous if they are used improperly. When the body loses fat free mass (FFM, made up of muscles, bones, and other tissues besides fat), it becomes more efficient at converting food into energy. This means that as the amount of FFM lost during dieting increases, the resting metabolic rate (RMR, the amount of energy required to maintain normal body functions while the body is at rest) decreases, and when the RMR decreases it becomes more difficult to lose weight. Since exercise can increase the amount of FFM (because exercise builds muscles), it has been used in combination with VLCDs in an attempt to prevent the loss of FFM that can occur during dieting. To determine whether endurance exercise (EE), weight training (WT), or endurance exercise and weight training (EEWT) alter weight loss and/or body composition, 69 obese females were placed on a liquid VLCD for 90 days. Twenty-six of the women followed the diet alone, 16 followed the diet with EE, 18 followed the diet with WT, and nine followed the diet with EEWT. During the diet period, body weight, body fat, FFM and RMR decreased. However, the decreases in body weight, body fat, FFM and RMR were the same for all groups, regardless of the use of or type of exercise. RMR decreased by between 7 and 12 percent for all diet groups. Small decreases in physical strength occurred in the women who followed the diet alone and diet plus EE, while small increases in strength were recorded for those in the WT and EEWT groups. It is concluded that adding exercises to the diet did not affect weight loss, loss of FFM or RMR. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Overweight persons, Obesity, Exercise, Exercise physiology, Body composition, Diet therapy, Low-calorie diet, Low calorie diet

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Plasma pyridoxal 5'-phosphate concentration and dietary vitamin B-6 intake in free-living, low-income elderly people

Article Abstract:

The blood level of Vitamin B-6 (pyridoxal 5'-phosphate) was measured and correlated with the dietary intake of Vitamin B-6 in a group of 198 low-income, largely caucasian (93 percent) individuals who were defined as elderly (age over 65). This is the first study which examines the blood level of this vitamin in an aged population and correlates this finding to dietary intake. Fasting blood levels were obtained from the volunteers, and a three day dietary history was recorded. The average dietary level of vitamin B-6 in the dietary records provided by the subjects showed that the women had a significantly lower vitamin B-6 intake than the men. The higher Vitamin B-6 intake of the men was due not to supplementation, but to the fact that they consumed larger quantities of food. Seventy-nine percent of the women and 75 percent of the men consumed less than the recommended daily requirement for Vitamin B-6. There was no direct correlation between dietary Vitamin B-6, age, sex, or general health, and the blood level of pyridoxal 5'-phosphate (PLP). Although three individuals reported taking supplemental B-6, the blood levels for PLP were not statistically different from those individuals who did not take supplements. For approximately one-third of this population the low level of PLP could be directly attributed to poor dietary level of Vitamin B-6. The study indicates that low or deficient levels of Vitamin B-6 may afflict many low-income elderly persons and are the result of inadequate dietary intake.

Aged, Elderly, Research, Diagnosis, Food and nutrition, Nutritional aspects, Vitamin B deficiency, Vitamin B complex, Deficiency diseases, Vitamin B in human nutrition

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