What is the biggest fat loser? That is the fastest way to lose body fat? Which exercises are the best for fat loss?

University of Edinburgh researchers reported that when subjects did 4-6 30-second sprints on a stationary cycle separated by four minutes of rest for just two weeks, their blood-glucose and insulin levels were reduced by almost 15% and 40%, respectively, and insulin sensitivity improved by about 25%, following consumption of 75 grams of glucose. Keeping insulin levels low and steady can help maximize fat-burning and minimize fat storage.

So even if you don’t have 20-30 minutes for a cardio workout, doing just 2-3 minutes of sprinting can at least help keep insulin down and fat-burning up.

Research from Australia found that out of 2,000-plus subjects who exercised vigorously for at least 2.5 hours per week, those who watched more than 40 minutes of television per day had higher waist circumferences than those watching less than 40 minutes. The scientists theorize that sitting for prolonged periods compromises the body’s ability to burn fat, which was shown by University of Missouri-Columbia researchers in both animals and humans. Avoid this slump by getting up and stretching at least every 20 minutes while sitting at work or at home.

Japanese scientists found that when subjects ate a 500-calorie meal while watching a 40-minute comedy show, their blood-glucose levels were much lower than when they consumed the same meal during a boring 40-minute lecture. The researchers suggest that laughter may have altered subjects’ brain chemistry in such a way that glucose entered the blood more slowly, or blood glucose was taken up by the muscles more rapidly. Try eating meals while watching something funny on TV to keep your blood-glucose and insulin levels low to help encourage fat loss.

Each pound of fat contains the equivalent of approximately 3,555 calories (McArdle et al., 1991).

The most fundamental aspect of any fat loss programme is to create a caloric deficit - to expend more calories than are consumed. Unfortunately, moderate aerobic exercise has only a moderate caloric requirement - around 187 calories per session (Utter et al., 1998). Based on this estimate, it could take up to 19 moderate aerobic workouts to lose just 0.45kg (1lb) of fat.

This might come as a surprise to those of you using the calorie counters on exercise machines to monitor energy expenditure during a workout. Unfortunately, these digital readouts are not always accurate. The most reliable way to assess energy expenditure during exercise is to measure oxygen consumption. Each litre of oxygen that you consume generates approximately five calories of energy. For example, if you were to exercise for 30 minutes and consume 30 litres of oxygen, you would have expended approximately 150 calories (five calories x 30 litres). Without directly measuring oxygen consumption, it's difficult to establish an accurate estimate of energy expenditure during a workout.

A second factor affecting the reliability of calorie counters is the difference between net and gross energy expenditure. Gross energy expenditure refers to the energy cost of exercise plus the metabolic rate. Net energy expenditure refers to just the energy cost of exercise. Calorie counters often display gross energy expenditure - so they don't accurately represent the additional energy that is used during exercise. In fact, during a 45 minute workout, net and gross energy expenditure can differ by almost 30% (Utter et al., 1998). The moral? Don't always believe what the machine tells you.

Another popular misconception is the idea that aerobic exercise increases caloric expenditure AFTER a bout of exercise, thus making a further contribution to fat loss. Unfortunately this is not always the case. Excess post-exercise oxygen consumption (the name given to the increase in caloric expenditure following a workout) is more likely to occur after high intensity exercise. Moderate aerobic exercise has very little effect on post-exercise metabolic rate (Sjodin et al., 1996). Furthermore, when an increase in physical activity results in a caloric deficit (as would occur with diet and exercise), there is evidence to show that the metabolic rate does not rise at all (Sjodin et al., 1996). What aerobic activity is good for is stopping you from putting the lost weight back on!

References
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McArdle, W.D., Katch, F.I., Katch, V.I. (1991). Exercise physiology. Energy, nutrition, and human performance (third edition). Lea & Febiger, Philadelphia, USA
McGuire, M.T., Wing, R.R., Klem, M.L., Seagle, H.M., and Hill, J.O. (1998). Long-term maintenance of weight loss: do people who lose weight through various weight loss methods use different behaviors to maintain their weight? International Journal of Obesity, 22, 572-577
Miller, W.C., Koceja, D.M., & Hamilton, E.J. (1997). A meta analysis of the past 25 years of weight loss research using diet, exercise or diet plus exercise intervention. International Journal of Obesity, 21, 941-947
Sjodin, A.M., Forslund, A.H., Westerterp, K.R., Andersson, A.B., Forslund, J.M., and Hambraeus, L.M. (1996). The influence of physical activity on BMR. Medicine and Science in Sports and Exercise, 28, 85-91
Utter, A.C., Nieman, D.C., Shannonhouse, E.M., Butterworth, D.E., & Nieman, C.N. (1998). Influence of diet and/or exercise on body composition and cardiorespiratory fitness in obese women. International Journal of Sport Nutrition, 8, 213-222