Measurement of ad libitum food intake, physical activity, and sedentary time in response to overfeeding

Abstract

Given the wide availability of highly palatable foods, overeating is common. Energy intake and metabolic responses to overfeeding may provide insights into weight gain prevention. We hypothesized a down-regulation in subsequent food intake and sedentary time, and up-regulation in non-exercise activity and core temperature in response to overfeeding in order to maintain body weight constant. In a monitored inpatient clinical research unit using a cross over study design, we investigated ad libitum energy intake (EI, using automated vending machines), core body temperature, and physical activity (using accelerometry) following a short term (3-day) weight maintaining (WM) vs overfeeding (OF) diet in healthy volunteers (n = 21, BMI, mean ± SD, 33.2±8.6 kg/m(2), 73.6% male). During the ad libitum periods following the WM vs. OF diets, there was no significant difference in mean 3-d EI (4061±1084 vs. 3926±1284 kcal/day, p = 0.41), and there were also no differences either in core body temperature (37.0±0.2°C vs. 37.1±0.2°C, p = 0.75) or sedentary time (70.9±12.9 vs. 72.0±7.4%, p = 0.88). However, during OF (but not WM), sedentary time was positively associated with weight gain (r = 0.49, p = 0.05, adjusted for age, sex, and initial weight). In conclusion, short term overfeeding did not result in a decrease in subsequent ad libitum food intake or overall change in sedentary time although in secondary analysis sedentary time was associated with weight gain during OF. Beyond possible changes in sedentary time, there is minimal attempt to restore energy balance during or following short term overfeeding.

Trial registration: ClinicalTrials.gov NCT00342732.

Figure 1. On admission volunteers were started on a standard weight maintaining diet for 4 days.

On days 5–7 volunteers were randomized to continue on their weight maintaining diet (WM) for an additional 3 days or start 3 days of an overfeeding diet (OF) equal to 150% of their weight maintenance diet in calories. During each 3 day diet period volunteers also wore accelerometers. On the final day of the WM or OF periods, volunteers were placed in the respiratory chamber for 24 hours for measurement of energy expenditure and they received the core temperature capsule. On days 8–10, ad libitum food was assessed using the automated vending machine. Following the 3 days of ad libitum food intake, volunteers resumed their weight maintaining diet for 3 days (as a wash out period) followed by another 3 days of either the WM or OF diet and once again followed by 3 days of ad libitum food intake using the vending machines.

Figure 2. Mean daily energy and macronutrient intake following weight maintenance diet (WM) and overfeeding diet (OF).

Fig. 2A. Daily energy intake during the study for each day. Ad libitum mean daily energy intake was 4061±1084 (kcal/d) following WM, and 3926±1284 (kcal/d) following OF. There was no difference in mean of daily energy intake (p = 0.4) between WM vs. OF. A decline in energy intake over 3 day ad libitum food intake period following OF is noted, but the trend was not significant (p = 0.9). Fig. 2B. Mean of daily carbohydrate, protein, and fat intake were 484±126 (g/d), 138±42 (g/d), 183±61 (g/d) following WM, and 477±156 (g/d), 129±45 (g/d), and 173±74 (g/d) following OF. No difference was found in carbohydrate (p = 0.7), protein (p = 0.2) or fat (p = 0.3) intake between WM vs. OF. All data are means ± SD. Paired t-test was used to analyze differences between diets.

Figure 3. Twenty four hour and sleep core temperature.

Mean 24 h (white column) and sleep (gray column) core temperatures were 37.0±0.2 (°C), 36.7±0.2 (°C) respectively on WM, and 37.1±0.2 (°C), 36.8±0.2 (°C) respectively on OF; both mean 24 h core temperature and sleep core temperature did not differ between WM and OF (p = 0.7 and p = 0.5), but mean 24 h core temperature were higher than sleep core temperature both on WM and OF (p = 0.008 and p = 0.008). Temperature data are means ± SD. Paired t-test was used to analyze differences between diets.

Figure 4. Comparison of sedentary time between weight maintenance diet (WM) and overfeeding diet (OF) and the correlation of sedentary time with age and weight gain during OF.

Figure 4A, Sedentary time shown on the inpatient unit and in the chamber on WM (70.9±12.9% and 74.6±10.6%, respectively)and on OF (72.0±7.4% and 78.4±6.6%, respectively). Sedentary time did not differ between WM Vs. OF on the inpatient unit or in the chamber, but increased while in the chamber vs. on the inpatient unit while on OF (p = 0.0005), not on WM. Figure 4B., Sedentary time was positively associated with weight gain during OF (r = 0.51, p = 0.03); Fig. 4C., Sedentary time shown in 24 hours in those with weight gain in top 10 and in bottom 10 percentile during OF. Time shown starting at midnight (0 on x-axis). Data shown as means ± SD. Comparison of sedentary time between diets analyzed using paired t-test; comparison between sedentary time on inpatient unit vs. chamber analyzed using t-test. R values are Pearson correlations.