What is under weight?

1.

Being under weight is define as having a body mass index BMI below 18.5 this is estimated to be less than the body mass needed to sustain optimal health.

2. Eat more calories when your body burns.

The most important thing to gain some weight is to create a calorie surplus meaning that you eat more calories then your body needed.

If you went to gain weight slowly try to hit 300 to 500 calories per day.

If you need to gain weight instantly so you have to eat more than and you eat in the past every person have a dream to gain weight and impress everyone by its body

If you want to gain weight fast aim for around 700 to 1000 calories above your maintenance level

Keep in mind that calorie calculator only provide estimates your needs may vary by several hundred calories per day give or take.

you don't need to count calories for the rest of your life but it has to do it for the first few days or weeks to get a feel for how many calories you are eating there are many great tools out there to help you .

Muscle is made of protein and without  it most of those extra calories may end up as body fat 

However keep in that protein is a double edged sword it's also highly feeling which may reduce your hunger and appetite  significantly.

If you are trying to gain weight aim for 0.7 grams of protein per pound of body weight

Highly protein food includes meats fish eggs many dairy products nuts and others

protein supplement like whey protein can also be used for daily diet to get enough protein in your diet 

Eat plenty of high crab and high fat foods to gain weight fast.. 

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