Energy balance intake

Tataranni, P. A., and Ravussin, E., 1997. Effect of fat intake on energy balance. Annals of the New York Academy of Sciences 819 37—43. 

Energy intake is only part of the equation. We can also adjust our energy balance by exercising. Various forms of exercise require different average energy outputs. Exercise involves doing thermodynamic work. The table in the next column Indicates that the amount of work depends on the type of exercise and the amount of mass being displaced. 

Specific caloric goals include adequate energy intake to promote growth and development in children, energy equilibrium and preservation of fat stores in well-nourished adults, and positive energy balance in malnourished patients with depleted fat stores. 

At least three peptides are implicated in the regulation of food intake, energy expenditure, and whole-body energy balance in both rodents and humans and are found both peripherally as hormones and centrally. These are galanin, neuropeptide Y, and... 

Obesity is a growing health problem in developed nations of the world. Approximately 33% of the population in the United States and 15% to 20% in Europe suffer from obesity.103 Human obesity has been linked to genes and other factors relevant to energy balance.104 The control of appetite and the mechanism of obesity are under investigation. The Ob-gene and its protein product, leptin, have been identified and appear to regulate food intake. 

PEM arises due to a negative energy balance, that is, a combined intake of proteins and calories less than that required for body expenditure. Inadequate food intake in PEM may have multiple causes, ranging from secondary malnutrition to sociopolitical problems (Fig. 24-2). 

Normal values range from 22 to 28. Values > 30 are indicative of an overweight condition. Obesity is always the consequence of a disturbed energy balance caloric intake exceeds consumption. Almost unavoidably, excess body weight and obesity lead to diseases and a shortened lifespan. 

It is generally accepted that the primary etiology of obesity concerns problems of energy balance as a consequence of nutritional excess and physical inactivity with less than 1% of cases associated with endocrine dysfunction (13). Changes in body weight or body composition depend on the relationship of energy intake to energy... 

Positive energy balance produces increases in body weight, body fat, or both. Weight loss occurs when expenditure exceeds intake. While the energy balance relationship is clear, application of the concept has not proven to be straightforward or easy. 

This chapter will review the relative contributions of exercise and food intake to changes in body weight and more specifically body composition. The emphasis of this chapter is on exercise as a modality for fat reduction and fat-free weight maintenance with the focus on aerobic exercise which has greater potential to modify body composition due to larger effects on energy balance. The first section reviews the effects of aerobic exercise on body composition in humans. The second section addresses techniques for measurement of body composition and limitations of these measurements in humans. The third section examines the use of experimental animals for studies of exercise and body composition, and the fourth section examines the interactions of diet and exercise. 

The study presented in Table III demonstrates that aerobic exercise alters energy balance and reduces body fat. The mechanism for this response was addressed by Mayer (65,66). He reported that exercise influenced energy balance by increasing caloric expenditure and by reducing appetite. Other studies have also reported that aerobic exercise produced appetite suppression, particularly in male rats (59,60). These investigators suggested that the effect was related to the intensity and duration of the exercise program. The food intake data for the study described in Table III are presented in Table IV and appear to support this conclusion. After only... 

Lay publications are inundated with fad diets designed to reduce body weight "quickly and easily" using a variety of caloric restrictions (68). Most individuals attempt to produce a negative energy balance and reduce body weight by decreasing food intake. 

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