Eat high-calorie whole foods. You should be getting your calories from nutritious whole foods that will give your body the right kind of fuel to build up your muscles fast. Foods high in sugar, bleached white flour, trans fats, and additives are high in calorie but low in nutrition, and they're going to build fat instead of muscle. If you want your muscles grow and look defined, you need to eat an array of whole foods from every food group.
Eat calorie-rich protein dishes like steak and roast beef, roasted chicken (with the skin and dark meat), salmon, eggs and pork. Protein is very important when you're building muscle. Avoid bacon, sausage and other cured meats, which contain additives that aren't good for you to eat in large quantities.
Eat plenty of fruits and vegetables of all kinds. They provide you with fiber and essential nutrients and help to keep you hydrated.
Eat whole grains like oatmeal, whole wheat, buckwheat, and quinoa instead of white bread, biscuits, muffins, pancakes, waffles and so on.
Eat legumes and nuts like black peans, pinto beans, lima beans, walnuts, pecans, peanuts, and almonds.
Eat more than you think you need. Do you eat when you're hungry, and stop when you're full? That sounds normal enough, but when your aim is to gain muscle fast, you need to be eating a lot more than you usually would. Add an extra serving to every single meal, and more if you can handle it. Your body needs the fuel to build muscle: it's as simple as that.
A good muscle-building breakfast might include a bowl of oatmeal, 4 eggs, 2 or more pieces of grilled ham, an apple, an orange, and a banana.
For lunch, you might eat a chicken sandwich on whole wheat bread, several handfuls of nuts, 2 avocados, and a big kale and tomato salad.
For dinner, have a big piece of steak or another protein, potatoes, vegetables, and second helpings of everything.
Eat at least 5 meals a day. Don't wait until your stomach is growling to eat again; you need to be constantly refueling your body when you're in a muscle-building phase. This isn't going to last forever, so try to enjoy it! Eat two additional meals in addition to breakfast, lunch and dinner.
Take supplements, but don't rely on them. You can't rely on muscle-building protein milkshakes to do the job for you. To build muscles, you need to be getting the vast majority of your calories from calorie-rich whole foods. That said, you can help accelerate the process by taking certain supplements that have been shown not to harm the body.
Creatine is a protein supplement that has been shown to help build bigger muscles. It comes in a powdered form, and you mix it with water and drink it a few times a day.
Protein milkshakes like Ensure are an OK supplement to have around for when you're having trouble eating enough calories between meals.
Stay hydrated. Working out as hard as you have to in order to gain muscle can dry you out quickly. Combat this by carrying a water bottle with you wherever you go, and drinking whenever you feel thirsty. Ideally, you should be consuming around 3 liters per day. Drink extra water before and after workouts.
Give up sugary or carbonated drinks. They won't help your overall fitness, and they might actually hold you back when it comes to strength training.
Alcohol isn't helpful, either. It dehydrates you and leaves you feeling low energy.
Get to know your body better. What's working, and what isn't? As you change your, pay attention to what's happening with your muscles. Everyone's different, and a food that might not do much to one person might be helpful for someone else. If you don't see improvements one week, switch it up and try something else the next week.