Fat loss in the cold--a controlled study.
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Adipose Tissue↗
Biomedical subjects
W J O'Hara
Publications and source records attributed to W J O'Hara.
Loss of body weight and fat during exercise in a cold chamber.
Ten men spent one week in a cold climatic facility performing a simulated arctic military exercise demanding an energy expenditure of 13-16 MJ-day-1. Although the ration pack was adequate, extensive plate wastage led to a negative energy balance of 2.2 MJ-day-1. Fluid intake was also insufficient, with a 3.25% decrease of body weight, and a 9.7% decrease in skin thickness over the cold exposure. Extensive fat mobilization was indicated by a decrease of skinfold thicknesses, an increase of body density, and associated ketonuria and glycosuria. The fat breakdown far exceeded the calculated energy deficit, and it is postulated that much of the "surplus" energy was required for synthesis of additional muscle protein. In the arctic environment, both energy and fluid balances are better maintained because there are few distraction from the simple pleasure of preparing and eating meals.
Adipose Tissue↗
Treatment of obesity by exercise in the cold.
Six obese men aged 25 to 46 years exercised vigorously for 3 1/2 hours in a cold chamber (-34 degrees C) on 10 successive days. There was an early water loss of about 1 kg, probably due to mobilization of glycogen stores, and a subsequent fat loss of about 4 kg (as estimated from readings of skinfold thickness and confirmed by underwater weighing). The total fat loss was much greater than the calculated external energy deficit (as estimated from dietary records, an activity diary and use of a Kofranyi-Michaelis respirometer). Although some energy was "wasted" through ketosis, much of the additional energy was apparently used for synthesis of additional muscle protein. Both readings of skinfold thickness and underwater weighing indicated that the loss of adipose tissue was well sustained in the first 2 months after the exercise program. Further experiments are recommended to determine whether cold exposure makes a specific contribution to the observed weight loss, and whether this approach would be equally effective in a larger and less selected sample of obese patients.
Adult↗
LaTulippe--a case study of a one hundred and sixty kilometre runner.
A 55 year old runner covered 160 km within a 20 hour period. His speed averaged 8.16 km/h, at an estimated 59.1% of maximum oxygen intake. After the first four hours of running, one of five fluids was taken in rotation every twelve minutes. Volumes ingested whe heart rate for the final four hours (125/min) was not increased relative to oxygen consumption for this portion of the run. Constancy of heart rate, continued urine production and formal fluid balance calculations all indicate that hydration was well maintained over the run. Caloric intake averaged 480 kcal/h (2.01 MJH), being greatest fro the ice-creas/syrup mixture; the energy deficit (56/KA/H, 235 kJ/h) was small during that part of the run in which food was provided.
Blood Pressure↗
Loss of body fat during an arctic winter expedition.
Fifty-five soldiers have been observed over a vigorous 10-day sledging patrol in the Canadian arctic and subarctic. Initial observations showed a low level of physical fitness (26% body fat, aerobic power 41.9 +/- 7.8 ml kg-1 min-1, handgrip force 43.7 +/- 7.2 kg). Over 2-week northern sojourn, energy expenditures as measured by a Kofranyi-Michaelis respirometer and diary observation averaged 3248 kcal (13.6 MJ) day-1, with a small (152 kcal (633 kJ)) positive daily energy balance. A weight loss of 1 kg, presumably water, was made good within 1 week of return to the south. A fat loss of some 3.9 kg was probably attributable largely to the demands of lean tissue synthesis. The lean mass was increased by 3.9 kg over the trial, with parallel gains of muscle force and aerobic power. The rapid mobilization of depot fat led to marked ketonuria.
Adipose Tissue↗