Nicolas D. Knuth
Towson University
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Publication
Featured researches published by Nicolas D. Knuth.
The Journal of Clinical Endocrinology and Metabolism | 2012
Darcy L. Johannsen; Nicolas D. Knuth; Robert Huizenga; Jennifer Rood; Eric Ravussin; Kevin D. Hall
CONTEXT An important goal during weight loss is to maximize fat loss while preserving metabolically active fat-free mass (FFM). Massive weight loss typically results in substantial loss of FFM potentially slowing metabolic rate. OBJECTIVE Our objective was to determine whether a weight loss program consisting of diet restriction and vigorous exercise helped to preserve FFM and maintain resting metabolic rate (RMR). PARTICIPANTS AND INTERVENTION We measured body composition by dual-energy x-ray absorptiometry, RMR by indirect calorimetry, and total energy expenditure by doubly labeled water at baseline (n = 16), wk 6 (n = 11), and wk 30 (n = 16). RESULTS At baseline, participants were severely obese (× ± SD; body mass index 49.4 ± 9.4 kg/m(2)) with 49 ± 5% body fat. At wk 30, more than one third of initial body weight was lost (-38 ± 9%) and consisted of 17 ± 8% from FFM and 83 ± 8% from fat. RMR declined out of proportion to the decrease in body mass, demonstrating a substantial metabolic adaptation (-244 ± 231 and -504 ± 171 kcal/d at wk 6 and 30, respectively, P < 0.01). Energy expenditure attributed to physical activity increased by 10.2 ± 5.1 kcal/kg.d at wk 6 and 6.0 ± 4.1 kcal/kg.d at wk 30 (P < 0.001 vs. zero). CONCLUSIONS Despite relative preservation of FFM, exercise did not prevent dramatic slowing of resting metabolism out of proportion to weight loss. This metabolic adaptation may persist during weight maintenance and predispose to weight regain unless high levels of physical activity or caloric restriction are maintained.
Cell Metabolism | 2015
Kevin D. Hall; Thomas Bemis; Robert J. Brychta; Kong Y. Chen; Amber B. Courville; Emma J. Crayner; Stephanie Goodwin; Juen Guo; Lilian Howard; Nicolas D. Knuth; Bernard V. Miller; Carla M. Prado; Mario Siervo; Monica C. Skarulis; Mary Walter; Peter Walter; Laura Yannai
Dietary carbohydrate restriction has been purported to cause endocrine adaptations that promote body fat loss more than dietary fat restriction. We selectively restricted dietary carbohydrate versus fat for 6 days following a 5-day baseline diet in 19 adults with obesity confined to a metabolic ward where they exercised daily. Subjects received both isocaloric diets in random order during each of two inpatient stays. Body fat loss was calculated as the difference between daily fat intake and net fat oxidation measured while residing in a metabolic chamber. Whereas carbohydrate restriction led to sustained increases in fat oxidation and loss of 53 ± 6 g/day of body fat, fat oxidation was unchanged by fat restriction, leading to 89 ± 6 g/day of fat loss, and was significantly greater than carbohydrate restriction (p = 0.002). Mathematical model simulations agreed with these data, but predicted that the body acts to minimize body fat differences with prolonged isocaloric diets varying in carbohydrate and fat.
Obesity | 2014
Nicolas D. Knuth; Darcy L. Johannsen; Robyn A. Tamboli; Pamela A. Marks-Shulman; Robert Huizenga; Kong Y. Chen; Naji N. Abumrad; Eric Ravussin; Kevin D. Hall
To measure changes in resting metabolic rate (RMR) and body composition in obese subjects following massive weight loss achieved via bariatric surgery or calorie restriction plus vigorous exercise.
Journal of the American Geriatrics Society | 2014
Jennifer A. Schrack; Nicolas D. Knuth; Eleanor M. Simonsick; Luigi Ferrucci
To assess the associations among age, health status, and resting metabolic rate (RMR) in a large population of older adults.
Journals of Gerontology Series A-biological Sciences and Medical Sciences | 2012
Luigi Ferrucci; Rafa de Cabo; Nicolas D. Knuth; Stephanie A. Studenski
HERACLES (Hercules according to the Romans) was probably the earliest and greatest body builder of all times and, without doubt, the greatest hero of Greek mythology. His conception, the result of a brief affair between the supreme deity Zeus and a mortal woman, made Zeuss wife Hera furious. She surreptitiously inserted two deadly snakes into Heracles crib. According to legend, that evening, a nurse found the delighted baby giggling and joyfully playing with a strangled serpent in each hand. Are stronger people already stronger at birth, as the Heracles legend seems to suggest? Is the destiny of our muscles already encoded in our genes (1)? Perhaps more importantly, what is the role of genetics as opposed to behavioral and environmental factors in the maintenance of muscle mass and strength with aging?
Obesity | 2017
Jennifer C. Kerns; Juen Guo; Erin Fothergill; Lilian Howard; Nicolas D. Knuth; Robert J. Brychta; Kong Y. Chen; Monica C. Skarulis; Peter Walter; Kevin D. Hall
The aim of this study was to explore how physical activity (PA) and energy intake (EI) changes were related to weight loss and regain following “The Biggest Loser” competition.
Journal of the American Geriatrics Society | 2012
Luigi Ferrucci; Jennifer A. Schrack; Nicolas D. Knuth; Eleanor M. Simonsick
European Journal of Applied Physiology | 2016
Devon A. Dobrosielski; Phillip Phan; Patrick Miller; Joseph Bohlen; Tamara Douglas-Burton; Nicolas D. Knuth
Medicine and Science in Sports and Exercise | 2018
Nicolas D. Knuth; Jennifer A. Schrack; Devon A. Dobrosielski
Medicine and Science in Sports and Exercise | 2016
Ariel F. Ross; Jennifer A. Schrack; Devon A. Dobrosielski; Nicolas D. Knuth