As heat waves roll like thunder across the country, more and more of us are passing up our coffee-shop baristas for juice bar blenderellas. Which is getting easy to do because juice bars are spreading like iPhones, promising natural energy, weight loss, and health. But that’s not always what you get. Here are the best and worst choices at some of the juiciest chains — along with tips for making the best drinks even better.

By the way, don’t even think about ordering a large. Although “small” varies from bar to bar, the smallest small here is 16 ounces — that’s two full cups. The “large” ought to be called ginormous (which, in case you haven’t heard, is now an official word; Webster’s just listed it).

JAMBA JUICE A small is 16 ounces.
The Best
Peach Perfection A blend of peaches, mangoes and strawberries
What makes it good: 200 calories, 0 grams fat
What makes it better: If you’re making this peach your liquid breakfast, ask for a scoop of fat-free yogurt to add some protein. And ask for some of the juice to be replaced with water to lower the sugar hit. This drink, which is otherwise both nutrish and delish, has 40 grams worth.
The Worst
The Peanutbutter Moo’d A fat and calorie sensation
What makes it baaaad: 530 calories, 11 grams of fat, and 83 grams of sugars. Enough said.

PLANET SMOOTHIE A small is 22 ounces.
The Best
Thelma and Louise A froth of strawberries, pineapple, and the Women’s Only blast
What makes it good: 226 calories and 0.2 grams fat  
What makes it better: Replace the blast with plain fat-free yogurt to up the skimpy 1 gram of protein, which will also give you some minerals and make it more filling.
The Worst
The Chocolate Elvis A bloated mix of chocolate, peanut butter, and bananas
What makes it baaaad: 522 calories and 9 grams of fat, more than anyone needs to slurp up. Carb-conscious? There are 108 grams of the stuff. Eek.

SMOOTHIE KING A small is 20 ounces.
The Best
Blueberry Heaven A blend of blueberries (antioxidant stars) and protein mix
What makes it good: 260 calories, 1 gram fat
What makes it better: Replace the protein mix with fat-free milk or yogurt; you’ll still get protein but also some calcium and other goodies. Then add Fiber Blend; combine its 8 grams of soluble fiber with what’s in the berries and you’ve likely met a third of your daily goal.
The Worst
The Hulk A vanilla, strawberry, or chocolate monster
What makes it baaaad: The innocent-sounding strawberry flavor has 953 calories and 29 grams of fat, more than half of it saturated — and yes, that is a small. The large? A belt-busting 1,906 calories and 58 grams. Okay, we know The Hulk is meant for people who want to gain weight (yes, it happens). But really, do they need lard-levels of fat???

The built-in reward for slurping up the best fruit smoothies? Most have at least a serving or two of fruit. And eating a diverse diet that includes 4 servings of fruit per day can make your RealAge as much as 4 years younger.
P.S. The next time you’re ordering at a juice bar…
…think of University of Miami sports nutritionist Lisa Dorfman, RD, or at least think of how she keeps her healthy fruit smoothies from turning into super-size mega-calorie shakes:
1. Downsize. Remember that small is the new large.
2. Up protein. Make that full feeling last longer by adding fat-free or low-fat yogurt, milk, or soymilk. Their protein slows the drink’s digestion.
3. Keep it real.  Dorfman skips most of the additives, enhancers, blasters, and boosters, finding fruit smoothies plenty healthy without mystery mix-ins. “Besides, you could have a negative reaction to stimulants like ginseng or guarana, or get much more of a vitamin or mineral than you need.”