Remember the '70s? Disco. Wooden platform sandals. And, everyone's favorite no-calorie sugar substitute: Sweet N' Low. Finally, we could wash down our cake with a can of Tab and still fit into our favorite bell-bottom jeans. That is, until researchers found out that our new go-to sugar substitute was linked to cancer and made us rethink those promising pink packets.

The scary news didn't stop new sugar swaps from hitting the shelves: NutraSweet, Equal and Splenda all promise us zero calories and the same sweet taste as the white stuff. But nutritionists aren't as keen on these sugar substitutes as we are. Researchers at Purdue University in West Lafayette, Ind. found that lab animals given foods sweetened with an artificial sweetener gained more weight than those who consumed sugar. The reason? Sugar substitutes give a shot of sweet taste with zero calories, which confuses the body. When we taste something sweet without getting the expected calories that come with that flavor, it actually makes us hungrier. So we eat more -- and pack on the pounds.

Skip ahead to see the best and worst sugar substitutes now.

Even natural sugar substitutes, which contain fructose, can wreak havoc on our health if we overindulge. "Very high doses of fructose may have a negative impact on the liver, and high dietary fructose is associated with metabolic syndrome, obesity, heart disease and type II diabetes," says Robin Foroutan, MS, RD, integrative nutritionist and communications chair for Dietitians in Integrative and Functional Medicine.

But let's face it: Living life without sugar isn't feasible. And with all kinds of sneaky sources of sugar (it's in ketchup, soy milk, tomato sauce and a laundry list of other foods you wouldn't expect) it's easy to overdo it. If you take your coffee with a teaspoon or two of the white stuff, you might want to reach for a sugar substitute every now and then. What's more, most sugar substitutes won't cause a spike in blood sugar levels, so you can sidestep the low energy and brain fog that usually follows a sweet treat.

Enter this list of the best and worst sugar substitutes out there. We asked dieticians to fill us in on the ones that aren't doing anything for our health, and the ones that (in moderation) are actually good for us.

In the early '70s, researchers found that rats who chowed down on saccharin were more likely to develop cancer than rodents who didn't. What's more, some experts believe the health effects aren't limited to lab animals. "Saccharin may add to the body's toxic load," says Foroutan. The chemicals found in artificial sweeteners like this one can cause inflammation, hormonal imbalances and chronic disease, such as diabetes, heart disease and cancer, she says.

Found in a whopping 6,000 foods (including cereals, sodas, and even your favorite sugarless gum), this sugar substitute has been scientifically proven to cause health problems in humans and animals. A study in the journal "Neurology" showed that some people are particularly susceptible to headaches caused by aspartame, while animal studies have linked this artificial sweetener to cancer. This sugar substitute is also a life-threatening no-no for people with Phenylketonuria (PKU), a rare condition in which the body can't break down phenylalanine, a main component of aspartame.

This sugar substitute has been approved since 1988, but you probably didn't know it's being used in your favorite foods and drinks (think ice cream and fruit juice), as well as personal care products, such as toothpaste and mouthwash. Look for it in ingredient lists as acesulfame K, acesulfame potassium, Ace-K or Sunett. According to celebrity nutritionist Lisa DeFazio, MS, RD, acesulfame K contains the carcinogen methylene chloride. "Long-term exposure can cause headaches, depression, nausea, mental confusion and even cancer," she says.

It seems we can have our cake and eat it, too. This zero-calorie sugar substitute has shown no harmful effects to humans. It also holds up well when heated, so you can safely add it to your grandma's famous whoopie pie recipe. But keep in mind, foods tend to bake faster when you've used sucralose, says Holly Kistler, RD, registered dietician at Cederquist Medical Wellness Center in Naples, Fla.