Gaining weight is probably a rare consideration for most, but there are people out there who struggle with their weight and not in losing it, but gaining it. It isn’t as simple as one might think.

There are several medical conditions that can cause unhealthy weight loss.

Here are a few of them:

Eating disorders: This includes anorexia nervosa, a serious mental disorder.
Thyroid problems: Having an overactive thyroid (hyperthyroidism) can boost metabolism and cause unhealthy weight loss.
Celiac disease: The most severe form of gluten intolerance. Most people with celiac disease don’t know that they have it (10).
Diabetes: Having uncontrolled diabetes (mainly type 1) can lead to severe weight loss.
Cancer: Cancerous tumors often burn large amounts of calories and can cause someone to lose a lot of weight.
Infections: Certain infections can cause someone to become severely underweight. This includes parasites, tuberculosis and HIV/AIDS.

Gaining weight, while optimizing health is huge obstacle within itself. You could try downing pints of ice cream, pasta, bread, cheeseburgers, and donuts, but I can promise you that isn’t the smartest way.

READ THIS: 5 Weight Gain Causes You Can’t Control

How to Gain Weight: 5 Ways to Gain Weight

Here are five ways celebrity nutritionist Cynthia Sass suggests you pack on the pounds:

1. Eat A Variety of Foods Every 4 hours

Supplying your body continuously with energy is key. Skipping meals is counterproductive as your body is constantly working day in and day out. When you deprive yourself of energy, your body is forced to use its stored fuel, muscle mass. Eat meals regularly to prevent losing. Consistency is key. Also, dining from at least three food groups or more is a good rule of thumb. Try getting some fruits, protein, and grains in with each meal. A wider variety provides your body with a broader spectrum of nutrients to work with throughout the day.