Yes, it is impossible to lose weight and burn fat in 3 weeks, and I will tell you how.
You can't cardio burn fat in 1 week but you can in 3 weeks. If you do exercise or cardio the body will use all the glucose first during the first week and then the body will start using fat storage afterwards.
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Food in fat and protein is what you need with less carbohydrate, it usually takes about 6 to 7 days for your body to reach the ketosis stage. Keto diet helps to minimise fat at a very rapid pace together with cardio. When you do 30 minutes of cardio workout or exercise you will burn about 150 calories. Workout for 3 weeks on a fitness simulator 3 - 4 times for half an hour, the intake will be 1,350 calories - 2,400 calories.
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