Effects on Thyroid and RMR Resulting From Very Low Calorie Diets (such as Kimkins)

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Effects of a very low calorie diet on weight, thyroid hormones and mood.

Wadden TA, Mason G, Foster GD, Stunkard AJ, Prange AJ.

University of Pennsylvania School of Medicine, Department of Psychiatry, Philadelphia 19104-3246.

Changes in weight, thyroid hormones and mood were examined in 15 obese (113 kg) women over an 18-week period. After 4 weeks of a 1200 kcal/day diet, patients were randomly assigned to one of two dietary conditions: very low calorie diet (VLCD) (n = 8) or balanced deficit diet (BDD) (n = 7). VLCD patients consumed 400 kcal/day for 8 weeks and then gradually returned to a 1200 kcal/day diet. BDD patients consumed 1200 kcal/day for the entire 18 weeks. Differences in weight losses between the conditions were statistically significant only during the consumption of the VLCD. Serum T3 decreased by as much as 66 percent in VLCD patients during consumption of the 400 kcal/day diet, whereas rT3 increased by as much as 27 percent. T3 increased when patients were realimented with a 1000 kcal/day balanced diet but remained a significant 22 percent below baseline at the end of the study. BDD patients also showed marked reductions in T3, as great as 40 percent, so that the differences between the two conditions were not statistically significant. Multiple regression analyses, collapsing across conditions (n = 15), indicated that weight loss at week 12 and baseline T3 accounted for 63 percent of the variance in the change in T3 at week 12. Patients in both conditions showed improvements in mood. Changes in depression were not associated with changes in serum T3.

Effects of a very low calorie diet on weight, thyr...[Int J Obes. 1990] - PubMed Result

Short and long term effects of a very low calorie diet on resting metabolic rate and body composition.Vansant G, Van Gaal L, Van Acker K, De Leeuw I.
Department of Endocrinology, Metabolism and Clinical Nutrition, University of Antwerp, Belgium.

Short and long term effects of a protein sparing modified fast (PSMF) diet on resting metabolic rate (RMR) and body composition were investigated. During a period of 6 months on diet, RMR decreased significantly, both in absolute value and after correction for fat-free mass (FFM). Short term evaluation with this type of diet showed no decrease in RMR. The results from this study indicate that the fall in RMR associated with a PSMF diet (weight loss) is not due to an acute adaptation to the lower energy intake. Changes in FFM are important in the change in RMR, but other factors have to be involved.

Short and long term effects of a very low calorie ...[Int J Obes. 1989] - PubMed Result

Sustained depression of the resting metabolic rate after massive weight loss
To assess potential long-term effects of weight loss on resting metabolic rate (RMR), the RMRs of seven obese women were measured by indirect calorimetry before weight loss, during a protein-sparing modified fast, and for 2 mo while at a stable reduced weight. Body composition was also determined at each interval. RMR significantly decreased 22% (p less than 0.01) with initiation of the modified fast. RMR values during the modified fast and during the maintenance diet at stable reduced weight were not different and all were significantly lower than the prediet RMR. Loss of lean tissue could not account for the decrease because changes in RMR per fat-free mass paralleled the total RMR reduction. A sustained decrement in RMR accompanied weight loss and persisted for greater than or equal to 8 wk despite increased caloric consumption and body weight stabilization.

Sustained depression of the resting metabolic rate after massive weight loss -- Elliot et al. 49 (1): 93 -- American Journal of Clinical Nutrition

Effect of a high-protein, very-low-calorie diet on resting metabolism, thyroid hormones, and energy expenditure of obese middle-aged women
A 4-6 mo study was conducted to examine effects of a very-low-calorie, high-protein diet and realimentation on energy expenditure, resting metabolic rate (RMR), and serum thyroid hormones of obese women aged 30- 54 yr. Fifteen healthy women, greater than or equal to 126% ideal body weight, were placed on the diet (420 kcal/day) and lost an average of 1.1 kg/wk until a predetermined goal weight was attained. RMR, triiodothyronine (T3), and reverse T3 decreased significantly (p less than 0.05). Thyroxine remained unchanged. Upon gradual realimentation onto solid foods, all metabolic parameters increased significantly within 5 wk toward pre-diet baseline values, but RMR (kcal/h) and T3 values remained significantly below pre-study values. Estimates of mean energy expenditure, utilizing a technique based on energy intake and body composition changes, averaged 1719 kcal/day during the diet period.

Effect of a high-protein, very-low-calorie diet on resting metabolism, thyroid hormones, and energy expenditure of obese middle-aged women -- Barrows and Snook 45 (2): 391 -- American Journal of Clinical Nutrition

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