Previous - Next
When CED subjects were
refed by providing energy supplements of 800 kcal (3.35 MJ) per
day (15 g protein, 35 g fat and 105 g carbohydrate) over a period
of 12 weeks, there was an overall increase in body weight (+ 1.9
kg) of which 1 kg was the increase in fat mass over this period
of time (SOARES et al., 1992). Nearly 70% of the total
increase in body weight occurred within the first 3 weeks. The
basal fasted RQs were significantly elevated (with values >
1.0) and so was the BMR both in absolute terms and when expressed
per kg FFM. The maximal rise in RQ was seen in the first 6 weeks
of supplementation, which was also the period of maximal increase
in fat mass (Figure 2). RQs and the substrate oxidation
rates, both in the fasted and the fed state, are summarised in Table
6. They show that there was a predominant increase in
carbohydrate oxidation, both in the fasted and fed state, and the
changes in RQ provided evidence of de novo lipogenesis during
this phase (ELLA and LIVESEY, 1988). Massive increases in
carbohydrate intake are known to result in high RQs (> 1.15),
with up to 25 % increase in BMR due to the cost of de novo
lipogenesis, even in the post-absorptive state (SCHUTZ et al.,
1982). Smaller rises in RQs during rehabilitation have been
documented in the Minnesota study and in other refeeding studies
of undernourished subjects (RAMANAMURTHI et al., 1962).
Table 6. Non-protein respiratory quotients (NPRQ) and substrate oxidation rates (SOR) in the fasted and fed state before and after 12 weeks supplementation in CED subjects
|
PRE- SUPPLEMENTATION |
POST SUPPLEMENTATION |
||
Fasted |
Fed |
Fasted |
Fed |
|
NPRQ |
0.943 |
0.994 |
1.035 |
1.089 |
SOR |
g/h |
g/h* |
g/h |
g/h* |
carbohydrate |
8.8 |
12.0 |
11.0 |
13.2 |
fat |
0.8 |
0.2 |
-0.5** |
-1.5** |
protein |
2.2 |
2.0 |
2.1 |
1.7 |
* Mean of 6 hours post-prandial.
** Negative fat oxidation is indicative of net lipogenesis.From PIERS et al., 1992c.
In
conclusion, it may be stated that the chronically energy
deficient or undernourished state is in many ways metabolically
different from the normal, well-nourished situation. There is a
predominant reliance on carbohydrate as metabolic fuel, even 12
hours after the last meal. This selective utilisation of
carbohydrate as substrate has possible metabolic advantages. The
preference for carbohydrate utilisation as fuel is seen also in
the fed state and during refeeding or energy supplementation and
is associated with de novo lipogenesis which may contribute to
the enhanced thermic effect of diets in these subjects.
I am grateful to Dr. M.
Elia for critical comments on the manuscript and Mr. J. Stubbs
for helpful discussion.
AHMED L., ROY N.C.:
Observations on the basal metabolism of healthy subjects under
varying conditions of temperature and humidity. Ind. J. Med.
Res., 26, 205-209 (1938).
BENEDICT F.G., MILES, W.R., ROTH, P., SMITH, H.M.: Human vitality and efficiency under prolonged restricted diet. Carnegie Institution of Washington, Washington, DC, 1919.
BLACK, A.E., PRENTICE, A.M., COWARD, W.A.: Use of food quotients to predict respiratory quotients for the doubly-labelled water method for measuring energy expenditure. Hum. Nutr.: Clin. Nutr., 40C, 381-392 (1986).
ELIA, M., LIVESEY, G.: Theory and validity of indirect calorimetry during net lipid synthesis. Am. J. Clin. Nutr., 47, 591-607 (1988).
ELIA, M., LIVESEY, G.: Energy expenditure and fuel selection in biological systems: The theory and practice of calculations based on indirect calorimetry and tracer methods. World Rev. Nutr. Diet., 3, 1-52 (1992).
FLATT, J.P.: Role of the increased adipose tissue mass in the apparent insulin sensitivity of obesity. Am. J. Clin. Nutr., 25, 1189-1192 (1972).
FLATT, J.P.: Dietary fat, carbohydrate balance and weight maintenance: effects of exercise. Am. J. Clin. Nutr., 45, 296-306 (1987).
FLATT, J.P., RAVUSSIN, E., ACHESON, K.J., JÉQUIER, E.: Effects of dietary fat on post-prandial substrate oxidation and on carbohydrate and fat balances. J. Clin. Invest., 76, 1019-1024 (1985).
FLIEDERBAUM, J.: Metabolic changes in hunger disease. In: Hunger Disease: Studies by the Jewish Physicians in the Warsaw Ghetto. Current Concepts in Nutrition, pp. 125-153, M. WINICK (Ed.). John Wiley & Sons, New York, NY, 1979.
GROOP, L.C., BONADOMMA, R.C., SHANK, M., PETRIES, A.S., DE FRONZO, R.A.: Role of free fatty acids and insulin in determining free fatty acid and lipid oxidation in man. J. Clin. Invest., 87, 83-89 (1991).
ISSEKUTZ, B., PAUL, P., MILLER, H.I., BORTZ, W.M.: Oxidation of plasma FFA in lean and obese humans. Metabolism, 17, 62-73 (1968).
KEYS, A.: The Biology of Human Starvation. Minnesota University Press, Minneapolis, MN, 1954.
LANDSBERG, L., YOUNG, J.B.: The role of the sympathoadrenal system in modulating energy expenditure. Clin. Endocrinol. Metab., 13, 475-499 (1984).
LIVESEY, G.: The energy equivalents of ATP and the energy values of food proteins and fats. Br. J. Nutr., 51, 15-28 (1984).
MUKERJEE, H.N., GUPTA, P.C.: The basal metabolism of Indians (Bengalis). Indian J. Med. Res., 18.ii, 15-28 (1931).
PIERS, L.S., SOARES, M.J., MAKAN, T., SHETTY, P.S.: Thermic effect of a meal. 1. Methodology and variation in normal young adults. Br. J. Nutr., 67, 165-175 (1992a).
PIERS, L.S., SOARES, M.J., SHETTY, P.S.: Thermic effect of a meal. 2. Role in chronic undernutrition. Br. J. Nutr., 67,177-185 (1992b).
PIERS, L.S., SOARES, M.J., KULKARNI, R.N., SHETTY, P.S.: Thermic effect of a meal. 3. Effect of dietary supplementation in chronically undernourished human subjects. Br. J. Nutr., 67,187-194 (1992c).
RAMANAMURTHI, P.S.V., SRINKANTIA, S.G., GOPALAN, C.: Energy metabolism in undernourished subjects before and after rehabilitation. Indian J. Med. Res., 50, 108-112 (1962).
SCHUTZ, Y., ACHESON, K., BESSARD, T. JÉQUIER, E.: Effect of a 7 day carbohydrate hyperalimentation on energy metabolism in healthy individuals. Clin. Nutr., 1, 75 (1982).
SCHUTZ, Y., TREMBLAY, A., WEINSIER, R.L., NELSON, K.M.: Role of fat oxidation in the long-term stabilization of body weight in obese women. Am. J. Clin. Nutr., 55, 670-674 (1992).
SCHWARTZ, R.S., RAVUSSIN, E., MASARI, M., O'CONNELL, M., ROBBINS, D.C.: The thermic effect of carbohydrate versus fat feeding in men. Metabolism, 34, 285-293 (1985).
SEN, R.N., BANERJEE, S.: Determination of basal metabolic rates and blood concentrations of protein-bound iodine, cholesterol and glucose in Indians. Indian J. Med. Res., 46, 759-765 (1958).
SHETTY, P.S.: Adaptive changes in basal metabolic rate and lean body mass in chronic undernutrition. Hum. Nutr.: Clin. Nutr., 38C, 443-451 (1984).
SHIV KUMAR, KUMAR N., SACHAR, R.S.: Basal metabolic rates in normal adult males. Indian J. Med. Res., 49, 702-709 (1961).
SOARES, M.J., SHETTY, P.S.: Basal metabolic rates and metabolic economy in chronic undernutrition. Eur. J. Clin. Nutr., 45, 363-373 (1991).
SOARES, M.J., PIERS, L.S., SHETTY, P.S., ROBINSON, S., JACKSON, A.A., WATERLOW, J.C.: Basal metabolic rate, body composition and whole body protein turnover in Indian men with differing nutritional status. Clin. Sci., 81, 419-425 (1991).
SOARES, M.J., KULKARNI, R.N., PIERS, L.S., VAZ, M., SHETTY, P.S.: Energy supplementation reverses changes in the basal metabolic rates of chronically undernourished individuals. Br. J. Nutr., 1992, in press.
SWAMINATHAN, R. KING, R.F.G., HOLMFIELD, J., SIWEK, R.A., BAKER, M., WALES, J.K.: Thermic effect of feeding carbohydrate, fat protein and mixed meal in lean and obese subjects. Am. J. Clin. Nutr., 42, 177-181 (1985).
WATERLOW, J.C.: The variability of energy metabolism in man. In: Comparative Nutrition, pp. 133-139, K. BLAXTER, I. MACDONALD (Eds.). John Libbey, London, 1988.