Friday, March 19, 2010

How much should I eat?

Let’s say you want to lose weight. You decide to hire a dietitian. She will try to calculate the amount of calories you are burning each day (due to metabolism and activity). Then she will tell you that you should eat slightly less than that to lose weight. If you are a man, she will most probably suggest you should eat 2500 calories, if you are a woman 2000.

Next she will break down this amount in protein/carbs/fats. First of all, she will teach you that 1 gram of protein contains 4 calories, 1 gram of carbs also 4 calories and 1 gram of fat 9 calories. Then she will usually tell you that 15% of your total calories should come from protein, 60% from carbs and 25% from fats. As a result, if you are a man, her advice will be: 375 calories from protein sources, 1500 from carbs, and 625 from fats (total 2500).

Finally, she will inform you that 100 grams of meat contain 30 grams of protein, 1 glass of milk contains 8 grams etc. In that way, she will give you a diet, with specific quantities for each food, that you will have to follow loyally each day.

Are you tired yet? So am I.

This approach is problematic on three counts. First, it’s too damn complex. Second, you will most probably lose weight, but you will not know what exactly did you lose (fat? muscle? something else?) Third, this diet is based on carbs – thus it’s wrong.

As we have already discussed, the base of our nutrition should be protein. This is the building block of our lean mass. The rule of thumb is that you need at least 0.5 gram of protein for each pound of lean bodyweight. If you exercise, you need more – up to a gram per pound. Thus, a 130-pound woman with 25% bodyfat (which means 97 pounds of lean mass) needs approximately 90 grams of protein if she exercises, and 45 if she doesn’t. This accounts for 360 (or 180) calories.

Let’s move to carbs. The rule here is to not exceed 100-150 grams, which is easily done if our only carb sources are fruit and vegetables. In that way, we keep insulin levels low, we provide just enough glucose to our body, and we educate it to burn fat for fuel. The only reason to consume more carbs is if we exercise too hard and too long, at which case we can go up to 200 grams. That means 800 calories max from carbs.

The rest of our daily calories (around 1000) should come from fats. And since 1 gram of fat contains 9 calories, we can achieve our goal with 100 grams of fat. This small quantity goes a long way to “top” our body with its favorite energy source.

That’s it. And for God’s sake, don’t get obsessed with grams of food. I hate these little scales. Learn to approximate your portions, and then try to consume these quantities on average each day.

Good luck!

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