Adrian Bryant shows you the 5 things to do to lose weight fast. You should be able to lose 20 lbs in 3-4 weeks. The first thing you should do is eat four small meals a day 3-4 hours apart. Before you eat each of your meals you should eat 2 raw vegetables and drink 1 serving of whey protein. You should next eat a meal that consists of no more than 300 calories based on your hunger level. You should avoid sugary foods like candy.