Is the lower-calorie version of a food your best bet? Not necessarily. When I started dieting, I always went for the lower-calorie choice; but as I learn more about food, I realize that it's not always the better or healthier choice. Here are a few "foods for thought:"

NUTS VS. CHIPS

Nuts are higher in calories than chips. One ounce of nuts has approximately 170 calories, whereas 1 ounce of chips is 130 to 150 calories. But chips are high in saturated fats and generally offer little nutrition. I realize people frown upon nuts because they can be high in calories, but if you limit yourself to five or 10, they are very satisfying. Many types have high amounts of mono-unsaturated fat, which is useful for regularizing blood lipids and protecting against cardiovascular deterioration. Plus, even a small amount packs loads of energy and protein.

In terms of weight control, although no study says definitely that nuts can help you lose weight, we do know that they don't make you gain. It's also possible that nuts help to control weight because of increased satiety. I find that eating just a few nuts and waiting a few minutes satisfies my hunger, while munching on chips just keeps me coming back for more.

WHITE POTATOES VS. SWEET POTATOES

White potatoes have 77 calories per 100 grams, while sweet potatoes have 86 calories for the same amount. So, gram for gram, they're pretty close; however, the sweet potato contains large amounts of the antioxidant beta carotene (vitamin A), a good source of vitamin B6, and has a lower glycemic load in spite of its sweetness. And while they both have fiber, the sweet potato wins here, too. On the other hand, while both are fine sources of potassium, the white potato is slightly better. And even though they both have vitamin C, the white potato has significantly more.

REGULAR PEANUT BUTTER VS. LOW-FAT PEANUT BUTTER

They have almost the same number of calories, but one has less fat. To make up for this taste-wise, however, the manufacturer increases the carbohydrates by using food additives (e.g. maltodextrin). For instance, Smucker's Natural Creamy Peanut Butter has 210 calories in 2 tablespoons with 6 grams of carbs, while Smucker's Natural Reduced Fat Creamy Peanut Butter has 200 calories with 12 grams of carbs. And keep in mind that peanuts have mostly good fat, so, in this case, there really is no reason to choose the low-fat version. Also, keep in mind that if you're looking for peanut butter, make sure to choose the all-natural kind without any partially hydrogenated oil.

OATMEAL VS. SPECIAL K

Just look at the ingredients in a product like Quaker Oats: 100 percent natural rolled oats — that's it. Now look at the ingredients in Special K: rice, wheat gluten, sugar, defatted wheat germ, salt, high-fructose corn syrup, dried whey, malt flavoring and calcium caseinate. And while Special K is fortified with vitamins and minerals, oatmeal is packed with natural nutritional pluses, including protein, iron, magnesium, zinc, manganese, thiamin and fiber.

Oatmeal is a bit higher in calories — half-cup of dry quick oats (about 1 cup cooked) has about 150 calories, whereas 1 cup of Special K has 110. But a packet of instant oatmeal contains only about 100 calories.

Not only that, researchers have shown that the soluble fiber in oatmeal may help to lower blood cholesterol levels and reduce the risk of heart disease when included in a diet that is also low in saturated fat and cholesterol. In terms of weight control, studies also show that an increase in fiber intake helps you feel full longer, thereby decreasing subsequent hunger. But be careful: Oatmeal can be a diet disaster if you start adding brown sugar, butter, honey and/or whole milk.

Finally, oats have virtually no sodium (other than the sodium you add), whereas Special K has 220 milligrams.

SUGAR-FREE CANDY VS. REGULAR CANDY

Hard candies have around 15 to 20 calories each, whereas the sugar-free varieties typically have half as many. Is it worth it? Well, if you don't have a problem with the sugar alcohols in sugar-free candy, you're probably fine. However, some people get stomach discomfort and/or a dreaded laxative effect.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.