The acute 1-week effects of the Zone diet on body composition, blood lipid levels, and performance in recreational endurance athletes.
The aim of this study was to examine the effects of a 7-day Zone diet compared with a normal diet on maximal oxygen uptake (V(O)2 max), running time to exhaustion during endurance performance, and body composition. Eight men, with the following physical characteristics (mean +/- SE), participated in this study: age, 26.1 +/- 1.9 years; height, 178 +/- 1.7 cm; mass, 70.7 +/- 2.1 kg; and V(O)2 max, 54.6 +/- 3.1 ml x kg(-1) x min(-1). All subjects undertook pretesting for V(O)2 max, time to exhaustion (80% V(O)2 max), and body composition (Biostat 1500) before following either the normal diet or the Zone diet for 7 days. These performance trials were performed before and after the dietary period. There was a significant (p < 0.05) decrease in total energy consumption from a mean of 2,314 +/- 334 kcal on a pretest diet to 1,994 +/- 438 kcal on the Zone diet. Subjects showed a significant reduction (p < 0.02) in body mass from 70.7 +/- 2.1 kg to 69.8 +/- 2.1 kg. In the 80% V(O)2 max time to exhaustion trial, there was a significant reduction (p < 0.05) in time to exhaustion from 37.68 +/- 8.6 minutes for the pretest diet to 34.11 +/- 7.01 minutes for the Zone diet. In conclusion, the claim of the authors of the Zone diet that performance time and V(O)2 max can be improved was not shown in this 1-week research trial. We would suggest that this is not a nutritional strategy that athletes should use until further work has been conducted.
Jarvis
Mark
M
Department of Life Sciences, Kingston University, Kingston KT1 2EE, England.
McNaughton
Lars
L
Seddon
Alan
A
Thompson
Dylan
D
D000328:Adult; D001823:Body Composition / Q000502:physiology*; D004032:Diet / Q000009:adverse effects / Q000379:methods*; D004033:Diet Fads; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D006801:Humans; D008055:Lipids / Q000097:blood*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D012016:Reference Values; D013177:Sports / Q000502:physiology*; D013647:Task Performance and Analysis
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D008055:Lipids