The Accelerated Fat Loss Bible Reviews & PDF free Download. Scientists from Newcastle University put this common misconception to the test. They took 3 groups of over overweight men and put them on a diet. The first group had it the toughest. They got no food – water only – for six days. The 2nd group followed a very low calorie diet (approximately 600 calories day) for 3 weeks. The 3rd group followed a slightly easier diet (1200 calories per day) for 6 weeks. All groups ended up losing approximately 5% of their bodyweight. The difference is how long it took. Group 1 did it in 6 days. Group two did it in 3 weeks. Group 3 did it in 6 weeks. No surprise there. But what IS surprising is that resting metabolism dropped the MOST in the six week diet group. The 3 week diet group saw the 2nd biggest drop in resting metabolism. And the 6-day fasting group saw the SMALLEST drop in resting metabolism! So the research is clear. Losing fat slowly is HORRIBLE for your metabolism.