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Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Body energy balance is regulated in adults. The accuracy of the phenomenon is particularly evident in laboratory animals under steady conditions. Moreover, it has been repeatedly demonstrated that this balance is maintained in spite of fluctuations in food intake or energy expenditure. When animals such as rats, dogs or rabbits are presented with a diluted or concentrated version of familiar food, they compensate rapidly by increasing or decreasing their ponderal intake. This is achieved first by a change in meal frequency, then meal size adapts to the new caloric content and meal frequency returns to the original pattern. This adaptation is based on the learning of post-ingestive cues. Hypo or hyperphagia leads to reduced or increased energy expenditure, as the case may be; the basal metabolic rate is modulated by thyroid hormones and diet-induced thermogenesis by the sympathetic system. These variations are partly regulatory. In a cold environment, the increase in energy expenditure caused by increased thermogenesis is rapidly compensated by increased caloric intake. Physical activity activates the sympathetic system responsible for numerous hormonal changes, the most important of which is insulin hyposecretion. In animals or humans, moderate aerobic exercise induces a small weight loss; afterwards, weight gain is normalized and increased caloric intake compensates for energy expenditures such as exercise, increased basal metabolic rate and diet-induced thermogenesis. Extreme changes in body weight and fat are produced by gestation and lactation; they are satisfactorily explained by concomitant hormonal changes. Especially during lactation, food intake is regulated so that it allows body weight to return to pregestation level. Studies on the mechanisms implicated in the regulation of body energy balance are still in progress. Friedman and Ramirez (1985) suggest that the way fatty acids are utilized is important. Kasser et al. (1985) show a striking difference in the cellular metabolism of hypothalamic regions, depending on the metabolic state or the animal, and Woods et al. (1985) strongly suggest a role for the central insulin level. These hypotheses are well-documented and not exclusive of each other.
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PMID:[Adaptation of food ingestion to energy expenditure]. 355 Sep 78

The existence of a set-point for homeostatic control of human body weight is uncertain. To investigate its existence, technically difficult determinations of energy expenditure must be performed: this has resulted in contradictory reports. The present study was performed with new methods in two stages (77 and 133 d respectively). Two healthy male subjects with rigorously controlled physical activity ingested three standardized diets of processed foods from the same manufacturer. Hypo-, iso- and hyperenergetic diets containing 6255 kJ (1494 kcal), 10 073 kJ (2406 kcal) and 13 791 kJ (3294 kcal) respectively were ingested during alternate periods; changes in body weight were measured. A new index of energy expenditure was calculated as the amount of weight lost in an 8 h overnight period (WL8H). A digital scale was used in stage 1 and a mechanical scale in stage 2. The change in body weight in response to the isoenergetic diet differed according to the circumstances. In basal conditions, it was associated with weight stability. After weight loss from energy restriction, the isoenergetic diet led to weight gain. After weight gain from overeating, it led to weight loss. Diets of higher energy content were associated with greater WL8H (F>20; P<0.0001 for both subjects). Measurement variability was lower using a mechanical scale. The present study demonstrates the existence of a homeostatic control of human weight and describes a new index of energy expenditure measured in weight units. It also demonstrates that strict dietary supervision for months is possible. Investigation of the human body weight set-point is vital in understanding obesity.
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PMID:Experimental demonstration of human weight homeostasis: implications for understanding obesity. 1546 60