This study shows that modified ADF is an effective, short term dietary intervention to help obese individuals lose weight and total body fat mass. Specifically, we show here that an ADF regimen resulted in a mean 7.1% weight loss of subjects from baseline after 6 wk of diet. Although CR is often used to facilitate weight loss [8
], many obese patients find it difficult to continue because food intake must be limited every day [10
]. The ADF is a new strategy that is capable for subject of self-selecting foods to continue their individual feed and fast day energy goals with the help of a dietitian for long time.
Our weight loss findings after 6 wk (6 ± 1.2
kg) are comparable to those of Varady et al. (5.6 ± 1
] and Eshghinia et al. (4.7 ± 2.5
kg) findings [12
]. Some researcher reported less weight loss due to shorter time of trial. Johnson et al. [13
] were shown 4
kg weight loss after 4 wk of ADF in overweight individuals.
According to these effects on body weight, ADF may be considered a suitable alternative to CR to help obese individuals lose weight in short period.
Waist circumference is associated with visceral obesity. Elevated intra-abdominal fat area is associated with elevated risk of coronary heart disease and type 2 diabetes [14
]. The ability of diet to reduce visceral fat mass has a protective role against theses chronic diseases. In our study, after 6
weeks of ADF diet, waist circumference as the visceral fat mass was reduced by 5.7% (p < 0.001) from baseline. In other studies visceral fat mass was reduced by 4–10% from baseline, that positively associated with body weight loss [4
Body composition changes only reported in three of the intermittent calorie restriction human trials with different methods [4
]. In our study, percentage body fat mass declined from 45.82 ± 4.16% at baseline to 42.98 ± 4.01% (p< 0.001) after 6
weeks. Varady et al. [4
] assessed fat mass with the same method (tetra-polar bioelectrical impedance analyzer) and reported decreasing of fat mass from 45 ± 1.6% to 42.1 ± 2% (P < 0.05) following 8
weeks ADF. Other trials had used dual-energy X-ray absorptiometry [17
The effects of 6 wk diet on blood pressure were also assessed. Systolic and diastolic BP were lowered (p< 0.05) by 9.7% and 8.3% respectively. Varady et al. [4
] reported 5.1% reduce in systolic BP after 8 wk intervention, whereas diastolic BP did not change. Eshghinia et al. findings suggested decrease in systolic and diastolic BP following 4 wk ADF intervention in mild to moderate hypertensive women [12
]. Results from another human study indicated that after 3 wk of intervention, neither systolic nor diastolic BP changed in subjects [16
However, animal data indicate that ADF is effective in decreasing fasting glucose and insulin concentrations, Human trials have noted mixed findings with ADF regarding glucoregulatory function [19
]. In this study, fasting glucose concentration decreased following 6
weeks ADF diet but was not statistically significant. Eshghinia et al. found that fasting glucose significantly reduces from baseline following 4 wk ADF in obese women [12
]. Heilbronn and colleagues [17
] noted a decrease in fasting insulin but no difference in fasting glucose after 22
days of ADF. In another study by the same group [20
] men on an ADF diet experienced a reduced insulin response to the test meal, but this effect was not observed in women. In addition, Halberg et al. [18
] found no change in fasting glucose or insulin concentrations in men following a 14-day ADF trial. Taken together, these findings about blood glucose concentration suggest that men and women may respond differently to ADF. It seems that in future studies should examine causes of the sex-specific differences noted above.
As a means of assessing cardiovascular response to ADF, trials in this area have examined heart rate, blood pressure, circulating lipids, and ischemic injury. In our study serum TG, total cholestrol and LDL concentration were lowered and HDL increased after 6
weeks. It is possible; these effects resulted from the decreases in body weight and fat mass. However these changes were not statistically significant. Heilbron et al. [17
] examined the effect of ADF on CVD risk in both sex. When subjects fasted on alternate days for 3 wk, circulating concentrations of HDL cholesterol increased in the women, whereas triacylglycerol concentrations decreased in the men. There is no clear explanation for these sex-based differences.
Other study reported different result. Varady et al. [4
] showed 21.2%, 24.8% and 32% reduction in total cholesterol, LDL and TG respectively but no changes in HDL after 8 wk ADF program. In Eshghinia et al. findings, fasting TG was not changed but total cholesterol, LDL and HDL decreased (P < 0.01). This lack of benefit effect of ADF on HDL cholesterol is not surprising because this cardioprotective lipid parameter is generally increase in response to exercise training [16
It should be noted that this trial and many of other ADF trials had not control groups, included limited subjects and less than 8
weeks duration. A randomized controlled trial with larger groups in longer time needs to test these findings. The next step in the ADF field will be to incorporate an exercise program into this diet to test more benefits effects in lipid profile.