Q: My boyfriend and I recently decided to start eating healthy together. After about six months of eating healthful meals (prepared by me!), he’s lost 15 pounds and I’m up five pounds. What am I doing wrong?

A: Great question!

First, kudos to you and your boyfriend for choosing to eat more healthfully and prepare more home-cooked meals. You’ve taken two significant steps toward a healthier lifestyle. Research shows it’s harder to eat healthy when you’re frequenting restaurants. Restaurant meals typically contain more fat, sodium and added sugars, while fruit, vegetables, whole grains and low- and non-fat dairy foods are often missing in action.

Much of the nutrition advice we hear today comes in sound bites, without the full context of how to apply the advice. One day you may hear “eat more protein,” the next day “eat less red meat.” Or you’ll hear, often because of the research report du jour making headlines, a specific eating plan touted, perhaps the Mediterranean diet or the value of going vegan.

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No wonder confusion reigns in the food and nutrition world. The reality is, though the science of nutrition continues to evolve (as does all science), we do know a lot about healthful eating. By the term “eating healthy,” I assume you try to follow the basic principles outlined in the 2010 Dietary Guidelines for Americans: Eat more fruits, vegetables, legumes, whole grains and low-fat dairy foods; lighten up on large portions of high-fat cuts of red meat and instead choose smaller portions of lean red meat, poultry or seafood; and eat less saturated fat and less added sugars.

But here’s the real question: How much food, regardless of whether it’s “healthy,” adds up to too many calories for you but not your boyfriend?

I’m going to wager that your boyfriend is taller than you and, just by virtue of being male, he’s got a larger frame with more muscle and less fat (muscle burns more calories than fat). And typically speaking, women require fewer calories than men. I know, bummer! (Bigger bummer: The older we all get, the fewer calories we burn.)

So it’s back to that simple calories-in-vs.-calories-out equation. If you eat more calories than your body burns, you’ll gain weight.

Here are a few practical pointers:

●Continue to choose healthful foods and prepare healthful meals, but eat less. Yes, portion control is key! How to do it? For starters, prepare less food. It’s so easy to overeat when that mouthwatering food is just a forkful away.

●Don’t serve family-style (platters of food on the table). Serve plates from the kitchen with just-right portions for each of you. If there happen to be leftovers or you’ve purposely cooked leftovers, put them away before you dig in. Consider brown-bagging them for lunch the next day or freezing leftovers for another weeknight meal in a jiffy.

●If cutting down on portions to trim your calorie total isn’t enough to steady your weight or help you shed a few pounds, add some exercise to burn more calories.

Good luck!

Warshaw, a registered dietitian nutritionist and certified diabetes educator, is the author of numerous books published by the American Diabetes Association and the blog EatHealthyLiveWell found on her Web site, www.hopewarshaw.com.

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