As summer’s heat moves in, it’s time for casual dress and laid-back dinners on the patio or porch. Foods lighten up, too, with a new crop of restaurant menus featuring more salads, grilled entrees, cold soups, frozen drinks and fruit for dessert.

The heat drives more diners to cool down with cold foods, and summer’s skin-baring fashions increase demand for waistline-friendly dishes and drinks.

Many restaurant salads aren’t the summer slimmers they may seem. Dietitian Jo Lichten, author of “Dining Lean: How to Eat Healthy When You’re Not at Home” (Nutrifit Publishing, $19.95 paperback), says take a good look at what is tossed into entree salads. “If you’re eating salads just to cut calories, stop and do the math. When you pile on the cheese, fried chicken, croutons, taco chips and salad dressing, you’ve probably eaten more calories than a large burger and fries.”

Remember that the principal ingredients in a salad are supposed to be fresh, raw vegetables, which are low in calories and a good source of fiber to keep you feeling full. Pick veggies in lots of colors to contribute a variety of nutrients to your diet. The fluid in fruits and vegetables helps keep you hydrated in the heat.

Add a total of 3 to 4 ounces of lean proteins such as boiled egg, grilled chicken or steak, steamed shrimp, seared tuna or deli-sliced roast beef, turkey or ham. Accessorize with a few nuts or small amount of grated Parmesan or crumbled goat cheese.

WHAT TO INCLUDE

● Look for menus that take advantage of summer’s bountiful harvest of low-calorie, nutrient-rich produce, including tomatoes, cucumbers, arugula, spinach, sweet onions, peaches, basil, strawberries and all kinds of other berries. Did you know that the vitamin C in produce is essential for building collagen for healthy skin? But don’t forget the sunscreen.

● Don’t be fooled by the fire. Grilled meats and fish are often slathered with butter or oil, so request that your order be brushed lightly with oil. Enjoy steak sauce and barbecue sauce — most brands have fewer than 20 calories per tablespoon. The fire in Mexican or Thai foods from fresh chiles comes from the powerful antioxidant compound called capsaicin. Research shows it boosts the metabolic rate a bit.

● Avoid cream-based cold soups, and go for bowls full of vegetables such as gazpacho. Fruit soups, from melon to strawberry, are delicious and nutritious summer menu additions.

● Instead of ice cream, you’ll save hundreds of calories per serving by choosing sorbets made with fresh fruit or frozen confections made with low-fat or nonfat milk. Some frozen yogurt outlets make their products with skim milk, so there are no grams of fat per serving. But watch out for empty calories in frozen ices, slushes and frozen “fruit” drinks made from colored, flavored sugar water. Look for frozen fruit pops made with frozen fruit. Some of the best are made by King of Pops and sold via street carts at farmers markets.

● Cocktail calorie cautions: Piña coladas may be popular poolside, but Lichten cautions that these high-calorie cocktails don’t belong anywhere near a bikini. “Instead of a piña colada, margarita or daiquiri [at 350-400 calories per 8 ounces], choose a light beer or wine spritzer [100 calories per 12 ounces] or wine, sangria or a rum and diet cola [80 calories per 4 ounces].”

Carolyn O’Neil is a registered dietitian and co-author of “The Dish on Eating Healthy and Being Fabulous!” Email her at carolyn@carolyn oneil.com.