White Foods
White rice, white breads, processed sugar, white pastas, skinless white potatoes, etc. These processed carbohydrate sources, which Americans are eating more of than ever before, lead to insulin burnout and are one of the main culprits in our obesity epidemic. And most have great, natural alternatives.

Trans Fats
Follow the lead of New York City and the Governator and eliminate them from your diet. Now. These man-made fats—typically found in fried foods and store-bought snacks and baked goods—lower good cholesterol (HDL) and raise bad cholesterol (LDL), leading to increased risk of heart disease, stroke, and diabetes. Simply stated, they will kill you.

Saturated Fats
Toss the animal-based sources of these artery cloggers, like fatty cuts of meat and whole-fat dairy products (ice cream, whole milk, creams, butter, etc.). Or at least strictly limit your intake.

Corn Oil
It's not the worst oil you could cook with. But it's not the best, either. In terms of good fats, bad fats, and flavor, olive wins.

Protein Powders
Research has shown no benefit to choosing protein supplements over natural dietary sources. Plus the convenience of these calorie-dense concoctions makes it more likely that you'll take on extra and store it as fat.

Energy Drinks
True, Red Bull and its ilk can jump-start your metabolism. But they've also been linked to cardiovascular problems, and some brands have been banned in other countries. Also, a recent Australian study suggests they can increase risk of blood clots, heart attack, and stroke.

Artificial Sweeteners
Ongoing medical debate over the carcinogenicity of these products means the jury's still out. In other words: The experts can't tell you for sure that this stuff won't cause cancer. Use agave nectar instead.