Did you know that increasing your metabolism can help you lose weight? So. How can you increase your metabolism? An easy way is to add lemon to your water. One lemon a day can improve your digestion, increase your metabolism, and help you lose weight. Give it a try. Here's what you do... Get yourself seven lemons for seven days. Start off your day by having some warm water with half of a lemon squeezed in. Throughout the day drink the other half of the lemon in either warm or cold water.