The Short and Long‐Term Effects of Food Restriction on Body Composition and the Renin Angiotensin System

Abstract

IntroductionIndividuals who experience severe food restriction (FR) diet are at increased risk for developing cardiovascular disease during the FR period and also long term well after the FR period has ended. Abnormalities in the heart, vascular system and kidneys including hypotension, bradycardia and mitral valve prolapse are common problems in individuals who have experienced a FR. Unfortunately, the long‐term risk for cardiovascular and renal disease due to earlier exposure to FR is an understudied problem and there are no known therapeutic strategies designed to prevent the increased risk after recovery from the FR period(s). The goal of this study was to determine the short and long term consequences of a severe FR diet on body composition and sodium and potassium balance.MethodsFour month old (mo) female Fischer rats were divided into a control (CT) group that had access to food ad libitum and a FR group that received 40% of the normal daily food intake. After 2 weeks, the FR rats received chow ad libitum for 1 month. The FR group were placed in metabolic cages on day 1 through day 4 and on day 14 of the restricted diet through day 4 of the recovery phase to collect urine and to determine the sodium & potassium balance.ResultsAfter 2 weeks, the FR group had an 18% reduction in body weight (BW) and a 50% reduction in water intake compared to the CT rats. In addition, plasma volume (p=0.03), blood pressure (p=0.03), heart rate (p=0.03), kidney weight, and kidney protein were all reduced and angiotensin (Ang) II (p<0.05) and angiotensinogen (p<0.001) were increased in the plasma. No differences were observed in plasma aldosterone and potassium or in urine protein. The plasma sodium concentration was increased in the FR rats. While the FR animals remained in sodium balance during the first 4 days of the diet, these animals were in negative balance for potassium (p<0.05) returning to balance on the 2nd day. The estrous cycle was disrupted after 3 days on the diet with the animals remaining in diestrus and returning to the ovulatory phase only after 7 days into the recovery period. The ad libitum diet also caused a positive balance for potassium during the 1st day without any effect on sodium balance. The rats did not recover their normal BW until 21 days into the recovery phase. Body fat recovered within 1 week while the % lean body mass did not recover until 28 days of the recovery phase.ConclusionSevere FR causes major changes in the renin angiotensin system, potassium balance, endocrine status and body composition. These effects are long lasting and likely contribute to the long term adverse consequences of exposure to a single period of severe food restriction.Support or Funding InformationTL1‐TR001431 (AVP), UL1‐TR001409 (KS) and R01‐HL119380 (KS, HJ).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.