Nutrient Amounts vs Percentages

Gretchen Becker Health Guide
  • Many diets rely on nutrient percentages to guide us in what we eat.


    For example, although nutritional recommendations seem to be slowly morphing from the low-fat, high-carbohydrate mantra of 15 years ago to a healthy-fat, unprocessed carbohydrate mantra and may go even further to recommend low-carbohydrate diets in the future, and although fats aren’t mentioned in the current iteration of the USDA’s MyPlate, many nutritionists still believe that fat is harmful and tell their clients to keep fat percentages under 30%, or saturated fat under 10%.


    But what exactly does it mean to limit the percentage of fat in your diet?

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    To illustrate the problem with nutrient percentages, I’m going to use two diets that have extreme amounts of calories: one with 500 calories and another with 4000 calories. Most of us would find a 500-calorie diet very difficult to maintain, and most of us know we shouldn’t eat as many as 4000 calories unless we’re playing a sport like football every day. I’m also going to use extreme percentages of fat.


    Let’s say the person eating 500 calories is eating 80% of those calories as fat, a number that would make many dieticians shriek with horror. But that’s 400 calories of fat, or 44 grams.


    Now let’s say the big eater, 4000 calories a day, is eating a “commendable” 20% of calories as fat. That would be 800 calories as fat, or 89 grams of fat, twice what the small eater with 80% fat calories is eating.


    OK, those are extremes, you might say. How about some more reasonable numbers.


    Well, someone eating 2500 calories a day and 29% fat, a diet that is close to guidelines for people who aren’t trying to lose weight, would be eating 725 calories as fat, or 81 grams.


    Someone trying to lose weight and eating only 1000 calories a day, with 80% fat, would be eating 800 calories as fat, or 89 grams of fat, not really that much more than the fat eaten by the person following guidelines and eating less than 30% fat.


    What all this means is that you shouldn’t jump through hoops to meet some nutrient percentage guideline. The percentages depend on how much food you’re eating every day as well as the composition of that food.


    If you think you should eat less fat, you can do it either by eating lots of tasteless low-fat products (which are usually higher in sugars and other carbohydrates to make them taste better), or you can eat full-fat products that taste better, but just eat less of them.


    I prefer a low-carbohydrate diet myself, so I’m not terribly concerned about fat. But I know that fat does contain calories, and I wouldn’t sit down and eat a couple of sticks of butter for dinner.


    Moderation as well as variety is important, the former to make sure we don’t gain weight when we don’t want to, and the latter to help us stick to our preferred way of eating for the long term. It’s important that we enjoy our food.

Published On: February 21, 2014