The following Mark's Daily Apple article was written by Mark Sisson,

and is narrated by Tina Lehman.

The genetics of obesity. Are you destined to be fat?

The entire promise of the primal blueprint

is enabling you to be the architect of your health and happiness. If we can identify the

environmental triggers and selective pressures under which the human genome developed, we'll have

a great roadmap for engineering our optimal lifestyle.

And for the most part, it works.

Not everyone will get the exact body they desire.

You won't all lose every extra pound.

I can't guarantee a six-pack or a complete eradication of baby weight.

But all in all, eating and living this way seems to produce good results. You can, it seems,

affect your health, body composition, and fitness. But genes still matter. And there's a large

trove of evidence showing that a person's genetics are really good at predicting their risk of

obesity. A 1990s study took 12 pairs of adult male identical twins, with identical genes,

determined their base metabolic rates and caloric needs, then overfed them by 1,000 calories

per day, six days a week, for 12 weeks. Mean weight gain was 8.1 kilograms ranging between

4.3 to 13.3 kilograms all over the board,

except for within the pairs of twins. When you compared one twin pair to another, weight gain was

very different. When you compared twins within a pair, the weight gain was extremely similar.

Not only that, but twins within a pair showed remarkable similarity in where fat was deposited, belly, hips, etc., and how much

body fat was actually accrued. Overall, there was three times more variance in the various

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