Ask the Diet Doctor: What's the Best Way to Measure Portions?
Keep your calories and waistline in control without obsessing over exact serving sizes
Q: What is the best way to measure my portions? Are cups or a scale more accurate?
A: This is a good question, as there are many ways to measure portions and control calories. The gold standard of portion control is weighing. When I helped run a nutrition clinical trial at Penn State University, we gave study participants all their food and drinks for about six months. We needed to control exactly what nutrients and how many calories each person ate, and to do this we weighed everything on digital scales. So if you want university clinical trial control, then you should weigh your food.
But do you need that kind of control? Probably not.
For most people, weighing food is overkill. It is time-consuming and not much fun, and these two things can drain your willpower. Even worse, the variability in measuring will simply drive you crazy.
You know weight loss is fundamentally about calories in versus calories out: You need to burn more calories than you take in. But the amount of calories that we burn on a daily basis and our ability to accurately measures them varies.
For example, let’s say our calorie-burning estimates are only accurate to +/- 15 percent. Even if your food measurements are 100 percent accurate, you will still be off by +/- 15 percent each day because of the variability and inaccuracy of our estimates of "calories out." As a result, you don’t need to be 100 percent accurate with your food measurements, and instead can use cups, tablespoons, and the like and still get the same results.
For most foods, the difference in measurement error between using a scale and using cups is less than the variability in our daily calorie expenditures, plus using cups is much easier and faster. If we use brown rice as an example, 100 grams of cooked brown rice is approximately a half-cup. Even if your measurements were off by 25 percent, you’d only be eating 25 more calories, a difference you could burn just by standing while taking phone calls during the day at work instead of sitting.
There are also lots of ways to estimate portion sizes of foods without weight them. Try these tricks that use everyday objects as comparisons to determine serving sizes.
If your weight loss has stalled and you are looking for ways to troubleshoot the problems, getting more control over your food intake and weighing your food may be warranted. But I try to use this as a last resort for regular clients, and it becomes more relevant for individuals that need to achieve rock-bottom body fat percentages due to their occupation or their sport’s requirements.
Aside from these situations with special populations, weighing your food is not worth the hassle and it won’t get you to your weight-loss goal faster.