When you're trying to gain weight, whether to move up a weight class in your sport or simply to pack on muscle, it can be frustratingly difficult to meet your daily calorie requirements. After all, you'd think that this sort of “license to eat” approach would be easy. Sometimes, though, it’s not. For one thing, there is a significant investment of time and money in getting, preparing and eating all the food necessary to hit your numbers. Second, just because you're trying to eat tons of calories this doesn't mean that you can devour everything in sight. In fact, it's even more important that you watch the quality of your calories while trying to gain muscular bulk – unless you're also willing to gain a significant amount of fat. For this reason, weight gainer powders can be an incredibly useful tool. Let's take a closer look at what's going on in the tubs of this stuff and see how you can make the best use of it. Figure Out Your Numbers The first thing you need to do is understand how many calories you need to reach your goals and how many grams of each macronutrient you can have. Typically, during bulking phases, people will follow a high-protein diet in order to make sure that their muscles grow more than their waists. To do this, you need to know how many calories your body burns when you're doing absolutely nothing – known as your Resting Metabolic Rate. The formula looks like this: Male: 9.99 x weight + 6.25 x height – 4.92 x age + 5 Female: 9.99 x weight + 6.25 x height – 4.92 x age – 161 weight in kilograms, height in centimeters, age in years But you aren't just sitting around doing nothing. Hopefully. So, now you have to figure out how many calories you burn on the average day – referred to as your Total Daily Energy Expenditure (TDEE). Here's the formula for that: RMR x Activity Factor

• Sedentary —desk job and little to no exercise (multiply by 1.2)
• Lightly Active — light exercise/sports 1–3 days/week (multiply by 1.375)
• Moderately Active — moderate exercise/sports 3–5 days/week (multiply by 1.55)
• Very Active — hard exercise/sports 6–7 days/week (multiply by 1.725)
• Extremely Active — hard daily exercise/sports and physical job or training (multiply by 1.9) 

In order to gain weight, you need to eat above your TDEE. Typically, the recommendation for this is to add 10 percent to your TDEE. Here's the thing about all this: Math is hard. Fortunately, there are tons of calculators online that do all the work for you. Understanding these numbers, though, will help you make wise use of your weight gainer powder to achieve your goals. Multi-Phase Proteins, Fats and Carbs When selecting a weight gainer powder, it's vital that you look at the ingredients and have a good idea of the quality of the calories involved. A main component of most products is going to be some form of protein, but not all protein powders are created equal. Unless you're vegan or otherwise adverse to dairy products, whey and casein are going to be your best options. These two milk proteins work together – whey offering a fast absorption while casein takes several hours to digest – to keep you properly nourished. Both whey and casein are also rich in healthy fats – particularly if they are sourced from organic, grass-fed cows. Studies have found that cows that are allowed to graze produce milk that is higher in omega-3 and conjugated linoleic fatty acids, both of which are healthy fuels for your brain and body. But a quality weight gainer will also come bundled with a carefully balanced carbohydrate. This is tricky. The carbs need to be provided in fairly high quantities to power the gains you're looking for, but they also need to absorb relatively slowly so that you're not totally crippled by extreme blood sugar crashes all day. To this end, many companies will use some form of maltodextrin – typically derived from wheat. This is an inferior ingredient, however, and will be an issue for anyone looking to avoid gluten. Instead opt for tapioca maltodextrin, which is easily absorbed and very rarely causes any allergic reactions. Read More: Choosing the Best Weight Gainer Supplement for your Goals Top 5 Best Foods for Mass Weight-Gain Protein Pancake Recipe You Will Want to Make Now