|Be a glutton from time to time!|
Needless to say that you cannot expect the same benign effects in subjects suffering from chronic diseases and/or those who are already obese.
Several previous studies have suggested that an energy intake that exceeds the energy expenditure for 2 to 8 weeks led to increased fat mass (FM) (Levine. 1998; Lammert. 2000; Joosen. 2005) - with no difference depending on whether the energy came from fat or carbohydrates, by the way (see Lammert. 2000). Moreover, the concept of non-exercise activity thermogenesis (NEAT) seems important in energy balance regulation as in the study, which overfed 16 non-obese subjects with 4.2 MJ/day for 56 days; changes in NEAT directly predicted resistance to FM gain from overfeeding (Levine. 1998).
Additionally, there is an association between weight gain and sedentary time during 3 days of overfeeding (He. 2012). Thus, activity energy expenditure is the most important component of energy expenditure to maintain body weightand composition during overfeeding. However, there is little detailed evidence of changes in body composition when AEE is maintained during overfeeding.
In the study at hand, however, where the body composition was evaluated at three time points: the day before the 3-day normal diet of the survey period (Baseline 1st [BL 1st ]); the day after the 3-day normal diet of the survey period (this day is the same measurement before overfeeding) (Baseline 2nd (BL 2nd )); and the day after the overfeeding diet period (Overfeeding (OF)), the 1,500kcal the subjects could get from whatever they wanted to eat (ad libitum overfeeding - that's news) didn't have a significant impact on the body composition of the men (see Figure 4 at the bottom to see which macros were increased).
How did the scientists ensure that the subjects actually got their 1,500 extra calories on a more or less "ad libitum" diat? All foods and beverages were weighed using a portable digital scale (KS-232; Dretec Co. Ltd., Saitama, Japan) during the BL 2nd and OF measurement periods (3 days). Furthermore, a survey of food intake was conducted using both self-reporting methods and visual records obtained using a digital camera or a mobile phone with a camera. A well-trained registered dietitian checked calculated nutrients from the diet records with the photographs. EI was measured daily from a week before the BL 1st until the OF measurement. All diet records were analyzed using a computerized nutrient analysis program (Excel Eiyoukun Ver. 4.5; Kenpakusha, Tokyo, Japan).In addition to the researchers' exact measurements, the subjects measured their own body weights twice daily for the 6 days (in the morning fasting and again before going to bed) from BL 1st to OF.
|Figure 1: Overview of the study design (Sagayama. 2014)|
Yes, the subjects stuck to the "no exercise prescription" and no, there was no post-study weight gain: If you look at the accelerometer data, you will see that there was no increase in activity level during the overfeeding period. In view of the fact that the subjects had to monitor their weight for additional 2 months and the scientists didn't report a subsequent change in body composition, you don't have to be afraid that the fat creeps on in the days after the overfeeding (Where should it come from, by the way?).Sagayama et al. first evaluated body composition and measurement reproducibility. None of the classic determinants of body composition, i.e. body weight (-0.2 ± 0.5 kg, P= 0.17; % fat = -0.1 ± 0.5%, P= 0.49; FM = -0.1 ± 0.4 kg, P= 0.36; TBW = -0.1 ± 0.4 kg, P= 0.56; FFDS = 0.0 ± 0.4 kg, P= 0.71). Changed over the course / in response to the the three day overfeeding period (for the statistic nerds: The intraclass correlation coefficient for all body composition values was above 0.9 and the coefficient variantion was less than 3%).
"Body weight, TBW, and FFDS increased during OF compared with BL 2nd measurements (Table 2 and Figures 2, 3, and 4; body weight = 0.7 ± 0.5 kg; TBW = 0.7 ±0.4 kg; FFDS = 0.0 ± 0.4 kg, P < 0.0001). There were no significant differences in FM and % fat between the BL 2nd and OF measurements (Table 2). Subjects measured their body weights during the postintervention period. All subjects returned to BL 2nd body weights within 2 weeks (5.0 ± 4.9 days)."I know this sounds crazy, but if you take a closer look at the individual changes in body mass and body fat, you will see that the majority of subjects lost a minimal amount of body fat.
|Figure 2: Body weight "gain" (mostly water; left) and fat loss (in all but two subjects; right) from baseline to post-overfeeding measurements (Sagayama. 2014)|
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