But back to portions. If you’re serious about losing or maintaining weight, you’d be wise to learn the size of a healthful portion of various categories of foods and treat what is typically served in restaurants to individual diners as servings for two or more. My “lean and mean” son and daughter-in-law in Los Angeles routinely order one entree for two people, and often have leftovers to take home for lunch the next day. In fact, my daughter-in-law usually requests a to-go container when the meal is ordered and packs up the excess food even before they dig in.

Still, Dr. Young insists — and I agree — that it’s far more helpful to prepare and eat most of your meals at home. You’ll know what’s in them (was that grilled fish you ordered prepared with a tablespoon of butter?) and how much lands on your plate. In fact, start by downsizing your dinner dishes to salad-plate size, and you can save nearly 600 calories a meal. Use measuring cups to dole out reasonable portions until you are able to eyeball them accurately. You might also invest in a kitchen scale to help you keep meat, poultry and fish servings to three or four ounces.

I know you’ve heard this before, but it bears repeating: Fill half or more of your plate with low-carbohydrate vegetables, like broccoli, cauliflower, spinach, green beans, carrots and brussels sprouts, and have a side salad with a dribble of dressing. Limit starchy vegetables like white and sweet potatoes (baked, not fried) and grains (whole, not refined) to a half-cup serving, one-cup max.

Dr. Young urges people to “get over their fear of carbs — if you’re eating the right kinds of grains in the right amounts, they don’t make you fat. They make you full — and provide you with a battalion of disease-fighting nutrients,” she wrote. But watch out for those oversized New York bagels, whole grain or otherwise, that are the caloric equivalent of six slices of bread.

Many people are unaware of how much, or how often, they eat. Keeping a food diary, recording everything you consume and where for a week or so, can help you recognize sources of mindless or excess consumption and their relationship to your feelings and circumstances.

Be wary of “nutrition halos” — foods deemed healthful but loaded with calories, albeit from healthy fats. A friend who moved to California gained 25 pounds in a year eating avocados from the tree in her yard. A serving of avocado is ¼ cup. Same for nuts, which, along with air-popped corn, are my favorite snacks.

At the same time, Dr. Young and I recognize the dangers inherent in feeling deprived of cherished, not-so-good-for you foods. When I was shedding those 40 pounds, I included one small treat a day — a few tablespoons of ice cream, a small cookie, a slice of quick bread, or sliver of cake or pie — lest after weeks of no treats I break down and devour half a cake or quart of ice cream at one sitting.