10 Reasons Skinny People Don't Gain Weight

Tell me if this situation sounds familiar...

You're sitting in the diner and a group of four, slender people slide in to the booth behind you. While you're sipping your coffee and forking your egg-white omelette, you overhear their orders: "Buffalo-chicken wrap with French fries; bacon-cheeseburger deluxe; macaroni and cheese; chipped beef special."

You inevitably and enviously wonder, "How are these people still so thin?"

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The answer to this question is both obvious and complex. Data shows that genetics is the greatest determinant of weight gain, influencing "about 40 to 70 percent of the variance in someone's susceptibility to obesity," notes Blanca Herrera who has a doctorate in human/medical genetics. Genetics influences metabolic rate and hormone sensitivity, which allow some people to naturally burn calories faster than others and better resist food cravings.

But there are reasons beyond genetics that contribute to weight gain (or lack thereof). Skinny people may be less sensitive to common food cues: While the sight of pizza or the smell of fried food might seduce some people into ordering an extra slice or a side of French fries, others are simply unfazed by these sensory enticements. Then there's daily activity. Simple daily movements, such as using the stairs rather than the elevator, walking the dog, or using a standing desk may seem insignificant, but over a long period of time they can burn a lot of calories. And some people just have a different relationship to food: There are those who simply eat to live, and others who absolutely live to eat.

Here are 10 reasons skinny people don't gain weight.