Abstract
Obesity is becoming one of the most severe global health problems. However, risk of developing normal weight obesity, where an individual has a high percentage of body fat despite a normal body mass index, is gaining attention since such individuals also develop systemic inflammation and metabolic dysregulation.In this study, juvenile (3-week-old) and adult (8-week-old) rats were fed a high fat diet (HFD) for 9 weeks and compared them with normal chow diet (NCD) fed rats. The HFD fed adult group showed increase in energy intake, body weight (BW), total fat, visceral fat and subcutaneous fat compared with an age-matched NCD group. In addition, the percentage of muscle mass to BW in the adult HFD group was significantly lower compared with the NCD group. When HFD feeding was started from the juvenile stage, there were almost no differences in energy intake and BW between the HFD and NCD groups. However, the juvenile HFD group showed a 1.7-fold increase in total fat, visceral fat and subcutaneous fat compared with their age-matched NCD group. The percentage of muscle mass to BW was significantly lower in the juvenile HFD group compared with the NCD group. In addition, increased plasma insulin levels and decreased insulin sensitivity was observed only in juvenile HFD group, but not in adult HFD group. These results suggest that HFD feeding in growth period induces insulin resistance and normal weight obesity.Here we show a method for generating a normal weight obesity model, as well as raising the alarm for developing normal weight obesity when children are exposed to high-fat meals.
Highlights
The prevalence of obesity is one of the most severe health concerns worldwide [1]
There were no significant differences in total energy intake (NCD; 3566.2 ± 87.3 kcal, high fat diet (HFD); 3402.8 ± 112.6 kcal) and body weight (BW) (Fig. 1c, F1, 294 = 0.04, P > 0.05) between the normal chow diet (NCD) and HFD groups during measurement
The effect of HFD on the glucose and insulin tolerance in juvenile and adult rats In the Adult rats, blood glucose in the HFD group was significantly higher at 30 and 60 min after glucose injection compared with the NCD group (Fig. 1e, F1, 24 = 6.18, P < 0.05)
Summary
The prevalence of obesity is one of the most severe health concerns worldwide [1]. “Obesity” is defined as body mass index (BMI) greater than or equal to 30 according to the World Health Organization classification, with abnormal or excessive fat accumulation that may impair health. Recent studies have revealed the high prevalence of individuals with normal weight obesity [2,3,4], which is defined as individuals with normal. The modern lifestyle is characterized by a lack of physical activity and excessive energy intake from high caloric diet in both children and adults. Animals, including human, are in a dramatic growth period and have very different energy metabolism and feeding regulations compared to adult animals [7]. We showed that neurons in the ventral tegmental area that regulate feeding and Maejima et al Nutrition & Metabolism (2020) 17:48 energy metabolism show undeveloped properties in weaning rats [7]. It can be considered that juvenile animals, which are in a dramatic growth period, are influenced by the balance of nutrition
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