Every time you fast or deprive your body of nutrients for more than 4 hours, your basal metabolic rate (BMR) slows and your body goes into starvation mode.

The symptoms of starvation are identical in the homeless wanderer, the religious zealot, the anorexic and the person who enjoys juice fasts at spas. They all experience the same effects: energy deprivation, slowed metabolic rate, lowered body temperature, reduced resistance to disease and rebound weight gain once feasting resumes. Juice fasts lower BMR because they eliminate from the diet vital food groups, including cereals and pulses that are sources of proteins and omega fats and are essential for energy, muscle repair and brain function. This, in turn, induces the starvation mode.

Much worse is the fact that because fasting temporarily causes the body to become leaner and leads to a drop in weight, dieters feel justified in using the starvation mode to quickly lose weight. But weight loss through fasting is largely because of depleting muscle mass and loss of water; the fat stores in the body increase, in fact, because of the slowed metabolic rate. What is required is a concerted effort to set the BMR right by eating at regular intervals and choosing high-energy foods that contain fibre and proteins, along with fruits and non-starchy vegetables—cruciferous vegetables like cabbage, cauliflower, broccoli, all kinds of beans, okra, those from the pumpkin and gourd families, and leafy greens like spinach and methi (fenugreek) for the main meals.

Understanding energy metabolism

Healthy habit: Eat at regular intervals to watch your waistline.

What happens during fasting

During a short fast of a day or so the body relies entirely on its stored glycogen for energy. First, liver glycogen is released and then muscle glycogen. If the fast continues beyond this stage, the body derives glucose by breaking down muscle and lean tissue into amino acids, which in turn synthesize glucose for energy. Body fat also breaks down to an alternative energy source—ketone bodies, which can support brain function to a certain extent. The appetite is severely suppressed and any food, whether it is vegetable juice, chapatti or fruit, is quickly diverted to be stored as fat. If starvation continues for long periods, a serious condition called ketoacidosis results. This is the uncontrolled production of ketone bodies, leading to a toxic accumulation of keto acids. This, in turn, acidifies the blood. It may cause severe fatigue, mental confusion and fruity breath, and this requires immediate medical attention.

Peak metabolism

• Don’t confuse fasting with weight loss. Long-term fasting induces fat storage, irrespective of the type of food you consume.

• Ensure that you eat every 3.5-4 hours to maintain healthy glycogen stores.

• Choose high-fibre, wholesome and protein-rich foods. Oats, bajra (pearl millet), tofu, seafood, eggs, legumes, spinach and other green vegetables all improve BMR and provide sustained energy.

• Avoid bingeing after long gaps between meals. Bingeing also increases the stores of body fat.

• Avoid overeating at one meal and skipping the next to make up for the extra calories—this will result in getting into the fasting and feasting extremes.

Madhuri Ruia is a nutritionist and Pilates expert. She runs InteGym in Mumbai, which advocates workouts with healthy diets.

Write to Madhuri at dietdesk@livemint.com.

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