Tendency of Death Following Dietary Restriction and Exercise Interventions for Body Weight Control in Diet-induced Obese Mice

Kim, Kijin; Lee, Wanglok; Ahn, Nayoung; Hong, Changbae; Kim, Sanghyun; Ko, Jinho

Abstract

BACKGROUND
Diet-induced obese mice were used as subjects in the course of experimental trial involving weight control. Unusual results were obtained by application of obesity treatment methods as in dietary restriction and exercise intervention.
METHODS
Subjects were the male mice C57/BL6 at the age of 4 weeks (n = 64, Orientbio Inc. Korea). Subjects were diet induced obese by consuming a 45% high fat diet (D12451, Research, Inc.) for 5 weeks, subjects were randomly assigned to 4 groups at the beginning of another 8 weeks. The four groups consisted of Control (no intervention), EX (exercise intervention), DR (dietary restriction) and DREX (dietary restriction and exercise intervention).
RESULTS
In the process of obese treatments, the amount of intake was markedly reduced in DR and DREX groups. Weights of DR and DREX groups went on decreasing from the 2nd week up to the 9th week. Weights of Control and EX groups decreased from the 2nd week continuing to the 4th week. Their weight started to increase, however, from then on. Mice in DR group died on the 6th week (n = 1), the 7th week (n = 2) and the 8th week (n = 2), but other mice lived on until the 9th week (n = 11). Mice in DREX died on the 6th week (n = 2), the 7th week (n = 5), the 8th week (n = 6) and the 9th week (n = 1), but only 2 mice remained alive on the 9th week. However, all of mice in Control and Ex groups stayed alive.
CONCLUSION
Mortality was noted during the course of obesity treatment in both dietary restriction group and in dietary restriction with exercise group. Taking this into consideration, excessive dietary restriction. seems to take part in negatively affecting cardiac overload, decline of immune function and increasing oxidative stress. In conclusion, not only the positive effects but also the negative side effects of weight loss, along with individual characteristics, should be taken into consideration. Further studies are needed to understand the negative effects of weight loss caused by excessive dietary restriction.