Hyper-alimentation - effects on health and well-being

Sammanfattning: The general aim of this thesis was to prospectively examine the effects on health and well-being when healthy normal weight individuals increase their energy intake, mainly from fast food and simultaneously adopt a sedentary lifestyle.This thesis is based upon a prospective experimental study design where 18 healthy normal weight individuals, 12 men and 6 women, aged 26 (6.6) years, increased their energy intake with in average 70 % during four weeks. Simultaneously their physical activity was limited to a maximum of 5000 steps per day. An age and gender matched control group (n=18), was recruited and asked not to change their eatingand physical activity habits for four weeks. Long-term follow-up measurements were performed after 6 and 12 months and 2.5 years after the intervention.During the intervention body weight increased with 6.4 (2.8) kg and measurements of body composition showed an increase of both fat mass and fat free mass after the intervention. Lower physical and mental health scores on SF-36 as well as depressive symptoms were found compared to baseline. They were temporary and when followed up 6 and 12 months after the intervention, physical and mental health had returned to baseline values, despite a somewhat increased body weight. The main essence of adopting an obesity provoking behaviour was lack of energy emerging from five structures: influenced self-confidence, commitment to oneself and others, managing eating, feelings of tiredness and physical impact. Laboratory measurements showed an increase of ALT above reference limits in 14 of the 18 participants during the intervention and HTGC increased, although this was not related to the increase in ALT levels. Twelve months after the intervention an increase of body weight with 1.5 (2.4) kg was found compared to baseline (p=0.018), fat free mass was unchanged compared to baseline while fat mass had increased, + 1.4 (1.9) kg (p=0.01). Two and a half years after the intervention an increase of body weight with 3.1 (4.0) kg was found compared to baseline (p=0.01), while there was no change in controls compared to baseline, + 0.1 (2.5) kg (p=0.88).Hyper-alimentation and limited physical activity during a short-term period of 4 weeks is sufficient to temporarily induce worsened HRQoL, cause depressive symptoms and lack of energy in healthy normal weight individuals. There were also temporary but clear effects on biochemical markers, suggesting that hyperalimentation per se can induce profound ALT elevations in less than 4 weeks. During the intervention both fat mass and fat-free mass increased while after 12 months there was only an increase of fat mass which was greater than expected from epidemiological studies. The marked difference between the increase in body weight in the intervention- and control group at 2.5 years also raises the question whether there is a long-term effect of increasing fat mass after a short period of hyperalimentation.