Although it is self-evident that the study of human nutrition has as its goal the optimal nutrition of man, the nutritional status of the body best suited to optimal performance, i.e., optimal nutrition, has unfortunately not yet been satisfactorily defined. Body composition of animals may be measured by direct chemical analysis and correlated with dietary intake and with the various aspects of performance; studies of body composition of living man, on the other hand, must rely on indirect measure ments. The following two reports, which give an account of the current status of the attack on the difficult task of measuring body composition in living man, are sponsored by the Committee on Nutrition to call attention to the resurgence of effort in this field during recent years. A fuller knowledge of the gross composition of the human body and its relation to preceding diet will constitute a significant step towards realization of the ultimate goal of nutritional science. Even then, a particular body composition will be of importance primarily in terms of functional performance. The availability of newer techniques should do much to stimulate physicians and nutritionists in defining body composition as an essential step in arriving at a more exact definition of optimal nutrition.

https://pediatrics.aappublications.org/content/pediatrics/29/3/476.full.pdf

Human body composition

For more than 200 years, the metabolic response that accompanies meal digestion has been characterized, theorized, and experimentally studied. Historically labeled “specific dynamic action” or “SDA”, this physiological phenomenon represents the energy expended on all activities of the body incidental to the ingestion, digestion, absorption, and assimilation of a meal. Specific dynamic action or a component of postprandial metabolism has been quantified for more than 250 invertebrate and vertebrate species. Characteristic among all of these species is a rapid postprandial increase in metabolic rate that upon peaking returns more slowly to prefeeding levels. The average maximum increase in metabolic rate stemming from digestion ranges from a modest 25% for humans to 136% for fishes, and to an impressive 687% for snakes. The type, size, composition, and temperature of the meal, as well as body size, body composition, and several environmental factors (e.g., ambient temperature and gas concentration) can each significantly impact the magnitude and duration of the SDA response. Meals that are large, intact or possess a tough exoskeleton require more digestive effort and thus generate a larger SDA than small, fragmented, or soft-bodied meals. Differences in the individual effort of preabsorptive (e.g., swallowing, gastric breakdown, and intestinal transport) and postabsorptive (e.g., catabolism and synthesis) events underlie much of the variation in SDA. Specific dynamic action is an integral part of an organism’s energy budget, exemplified by accounting for 19–43% of the daily energy expenditure of free-ranging snakes. There are innumerable opportunities for research in SDA including coverage of unexplored taxa, investigating the underlying sources, determinants, and the central control of postprandial metabolism, and examining the integration of SDA across other physiological systems.

/pdf/specific-dynamic-action-a-review-of-the-postprandial-18gdectymp.pdf

Specific dynamic action: a review of the postprandial metabolic response

The mechanisms involved in body weight regulation in humans include genetic, physiological, and behavioral factors. Stability of body weight and body composition requires that energy intake matches...

https://www.physiology.org/doi/pdf/10.1152/physrev.1999.79.2.451

Regulation of Body Weight in Humans

I. Introduction II. Criteria for Evaluating the Efficacy of Antiobesity Treatment III. Physiological and Pharmacological Mechanisms to Reduce Food Intake A. Peripherally acting agents B. Centrally acting agents IV. Drugs That Alter Metabolism A. Preabsorptive agents B. Postabsorptive modifiers of nutrient metabolism V. Drugs That Increase Energy Expenditure A. Thyroid hormone B. Adrenergic thermogenic drugs VI. Conclusion

/pdf/current-and-potential-drugs-for-treatment-of-obesity-2vzpf4l3j3.pdf

Current and Potential Drugs for Treatment of Obesity

The intake of nutrients is known to increase energy expenditure. Measured thermic effects of nutrient are 0-3% for fat, 5-10% for carbohydrates and 20-30% for proteins. Stimulation of adenosine triphosphate (ATP) hydrolysis during intestinal absorption, initial metabolic steps and nutrient storage are responsible for this food thermic effect. The autonomic nervous system modulates the thermic effect of nutrients. Parasympathetic muscarinic antagonists reduce the thermic effect of orally administered nutrients, most likely by delaying gastric emptying and decreasing the amount of nutrient storage. Antagonists of the beta-adrenoreceptors decrease the thermic effect of glucose. The part of glucose induced thermogenesis which is eliminated by beta-adrenergic antagonists has been called 'facultative thermogenesis' and takes place, at least in part, in skeletal muscle. Insulin-induced stimulation of muscle sympathetic nerve activity may be involved in this facultative thermogenesis. The thermic effect of food is reduced in obese, insulin-resistant patients. The effect of thermogenesis represents about 50-150 kcal/day in such patients, and can explain only a minor part of their excess body weight. Defective thermogenesis may, however, contribute to weight gain, or impair weight loss in such patients.

/pdf/thermic-effect-of-food-and-sympathetic-nervous-system-27kb7nrbzo.pdf

Thermic effect of food and sympathetic nervous system activity in humans

Seven lean healthy young men were studied for 6 weeks during exposure to pharmacologic inhibition or stimulation of the sympathetic nervous system. For a period of 2 weeks their β-adrenergic receptors were either blocked with propranolol hydrochloride (160 mg/d) or stimulated with terbutaline sulphate (15 mg/d). After a further 2 weeks of placebo administration (500 mg lactose/d), the subjects crossed over to the drug they had not been taking at the beginning of the experiment for another 14 days. During the last five days of each 2-week period, the subjects consumed a weight-maintaining diet, composed of 12% protein, 48% carbohydrate, and 40% fat. They consumed exactly the same menus on the same days during the subsequent study periods. Body weight and physical activity were measured every day for 6 weeks. Daily heart rate and nitrogen excretion were measured continuously for four days at the end of each 2-week period, the last two days of which were spent in a respiration chamber where energy expenditure and a variety of metabolic parameters were measured. In the respiration chamber on the propranolol, placebo, and terbutaline treatments, respectively, significant differences were observed in mean daily heart rate (65 ± 3,75 ± 4, and 84 ± 4 beats/min), mean sleeping heart rate (51 ± 2, 56 ± 3, and 62 ± 3 beats/min), nitrogen excretion (13.6 ± 0.7, 12.6 ± 0.6, and 11.9 ± 0.6 g/d), fat oxidation (+1,045 ± 95, +1,243 ± 148, and +1,278 ± 84 kcal/d) and thyroid hormones (12.0 ± 0.7, 15.7 ± 0.9, and 17.2 ± 1.0 T3/T4 ratio). Although a 24-hour energy expenditure tended to be lower with propranolol (2,820 ± 187 kcal/d) than with the placebo (2,884 ± 174 kcal/d) and terbutaline (2,880 ± 122 kcal/d) treatments, the difference was not significant. The results are discussed in relationship with the possible use of β-adrenergic receptor agonists in the treatment of obesity.

Two-week stimulation or blockade of the sympathetic nervous system in man: influence on body weight, body composition, and twenty four-hour energy expenditure.

After 13 days of weight maintenance diet (13,720 +/- 620 kJ/day, 40% fat, 15% protein, and 45% carbohydrate), five young men (71.3 +/- 7.1 kg, 181 +/- 8 cm; means +/- SD) were overfed for 9 days at 1.6 times their maintenance requirements (i.e., +8,010 kJ/day). Twenty-four-hour energy expenditure (24-h EE) and basal metabolic rate (BMR) were measured on three occasions, once after 10 days on the weight-maintenance diet and after 2 and 9 days of overfeeding. Physical activity was monitored throughout the study, body composition was measured by underwater weighing, and nitrogen balance was assessed for 3 days during the two experimental periods. Overfeeding caused an increase in body weight averaging 3.2 kg of which 56% was fat as measured by underwater weighing. After 9 days of overfeeding, BMR increased by 622 kJ/day, which could explain one-third of the increase in 24-h EE (2,038 kJ/day); the remainder was due to the thermic effect of food (which increased in proportion with excess energy intake) and the increased cost of physical activity, related to body weight gain. This study shows that approximately one-quarter of the excess energy intake was dissipated through an increase in EE, with 75% being stored in the body. Under our experimental conditions of mixed overfeeding in which body composition measurements were combined with those of energy balance, it was possible to account for all of the energy ingested in excess of maintenance requirements.

Short-term, mixed-diet overfeeding in man: no evidence for "luxuskonsumption"

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

L. Bourquin

Author Tools

Chat about Author

Papers

Two-week stimulation or blockade of the sympathetic nervous system in man: influence on body weight, body composition, and twenty four-hour energy expenditure.

Short-term, mixed-diet overfeeding in man: no evidence for "luxuskonsumption"