The fasting periods were often called ‘cleanses’, ‘detoxifications’, or ‘purifications’, but the idea is similar – e.g. to abstain from eating food for a certain period of time, often for health reasons. People imagined that this period of abstinence from food would clear their bodies’ systems of toxins and rejuvenate them. They may have been more correct than they knew.
Make sure that you don't get hungry by eating small portions throughout the day at regular intervals. Between your meals, eat a 150-calorie snack to keep your metabolism burning and to stave off hunger. Be sure that you don't eat a fattening snack such as sweets or crisps. When you're hungry, your body conserves calories and slows down your metabolic processes.
Be choosy about carbs. You can decide which ones you eat, and how much. Look for those that are low on the glycemic index (for instance, asparagus is lower on the glycemic index than a potato) or lower in carbs per serving than others. Whole grains are better choices than processed items, because processing removes key nutrients such as fiber, iron, and B vitamins. They may be added back, such as in “enriched” bread.