Loss of Weight, Sodium and Water in Obese Persons Consuming a High- or Low-Carbohydrate Diet

Abstract

Isocaloric 5.61 mJ (1,340 kcal) formula diets involving the isocaloric exchange of fat and carbohydrate were fed to 21 obese persons selected for sex, height, and weight before the start of the treatment and distributed over three groups. The weight loss observed during the carbohydrate-restricted diets was significantly greater than during the high-carbohydrate diet. After 28 days of treatment the weight loss recorded on the high-carbohydrate diet was 9.5 ± 0.7 kg, as compared to 11.4 ± 0.7 kg (p < 0.05) on the corn oil-containing diet and 12.5 ± 0.9 kg (p < 0.01) on the butter-fat-containing diet. The weight loss achieved was not dependent on the type of fat administered (saturated vs. polyunsaturated). When calculated cumulatively, sodium excretion during the first 7 days was significantly greater on the low-carbohydrate diet, whereas after 28 days the total amount of sodium excreted was highest on the high-carbohydrate diet. Potassium excretion during the low-carbohydrate diets was significantly greater for as long as 14 days, but at the end of the experimental period the observed differences no longer attained statistical significance. At no time did the intake and loss of fluid and the balances calculated therefrom show significant differences. From the findings obtained it appears that the alterations in the water and electrolyte balance observed during the low-carbohydrate diets are reversible phenomena and should thus not be regarded as causal agents of the different weight reduction.

Effects of Incremental Dietary Macronutrient Changes on Fat Oxidation and Body Composition

“…Researchers believe consuming the low-carbohydrate diet first did not provide an order effect. Similar results of weight changes have been observed in obese subjects participating in a crossover study consuming hypocaloric macronutrient-different diets (Rabast, Vornberger, & Ehl, 1981), implying less fat mass loss while consuming a high carbohydrate diet would have occurred even if the diets were to have been reversed. Additionally, if the caloric deficit is able to explain the initial weight loss, feeding the diets in reverse order (high carbohydrate to low-carbohydrate) may have maintained the rate of fat mass loss through a lower RQ as carbohydrate consumption decreases.…”

Acid-base analysis of individuals following two weight loss diets

“…Several studies have confirmed ketonuria by urine dipstick or ketonemia by measurement of serum b-hydroxybutyrate in subjects following a low-carbohydrate diet (Azar and Bloom, 1963;Young et al, 1971;Rabast and Kasper, 1978;Rabast et al, 1981;Volek et al, 2002;Brehm et al, 2003Brehm et al, , 2005Meckling et al, 2004;Yancy et al, 2004;Boden et al, 2005). Furthermore, some data suggest an inverse relationship such that urinary ketone body levels increase as carbohydrate intake decreases (Young et al, 1971).…”

“…Nearly all cell types in the human body can use these alternative fuels although some (e.g., myocardium) prefer fatty acids, whereas others (e.g., brain) can only use ketone bodies. Ketone bodies are detectable in the serum, urine, and breath (Azar and Bloom, 1963;Young et al, 1971;Rabast and Kasper, 1978;Rabast et al, 1981), and in fact, urine and breath ketone body tests are sometimes used to monitor for adequate carbohydrate restriction by lowcarbohydrate diet followers (Larosa et al, 1980). Ketone bodies have an acidic pK and are best known for causing ketoacidosis, a serious condition that can cause acidemia in diabetic and alcoholic patients.…”

Quantification of the effect of energy imbalance on bodyweight

“…However, apart from a few notable exceptions, 61–63 most results from inpatient studies with adequately controlled diets have shown little effect of diet composition on bodyweight and fat-mass changes. 64–69 These results therefore show the exquisite regulation of metabolic fuel selection to adjust to the macronutrient content of the diet.…”