And we don't mean with a martini. "Hydration is key in keeping your metabolism high and your body functioning as a fat burning machine," Karena and Katrina say.

According to the fitness experts, dehydration causes fatigue, a slowed metabolism (yikes) and unhealthy cravings. The worst part? When you're dehydrated, your body can't burn fat efficiently, which means all of your hard work in the gym and the kitchen goes unnoticed.

"Make those workouts and healthy meals count by drinking plenty of water," Karena and Katrina say. "It's essential to drink at least half of your body weight in ounces daily." This means if you weigh 150 pounds, you're drinking 75 ounces of water throughout the day.

Yeah, yeah, we've all heard that breakfast is the most important meal of the day, but according to the Tone It Up duo, going for a run before you chow is an effective way to lose body fat fast. Ever heard of the term fasted cardio? It's a method regularly used by fitness competitors to get a jump-start on burning body fat -- and there's a reason they stick to it. "Exercising first thing in the morning -- before you've eaten -- is best for slimming your waistline," Karena and Katrina say. "When you wake up, your body is in a fasting state. If you work out before whipping up breakfast, it ups the level of fat oxidation." For those who don't speak fitness expert, this means burning fat for fuel.

For those who aren't familiar with high-intensity interval training (HIIT), this workout boosts the heart rate with quick, high-intensity bursts of exercise in between intervals of low-intensity activity (think: jogging with sprints). Why is this effective in losing body fat? Because it doesn't require hours of cardio (which wears and tears at the muscle, rather than building it) and confuses the body by getting it out of the steady state it goes into when you've been running on the treadmill for a half an hour. Instead, your body is forced to exert more energy, thus resulting in losing body fat.

"This is one of the most effective ways to burn fat," Karena and Katrina say. "It's usually a high-energy workout that includes intense cardio moves, which burns major calories." Incorporating even a 20-minute HIIT workout can be supereffective for those looking to lose body fat. Try this HIIT workout to torch your love handles.

Stay strong, ladies. Picking up the weights will build your muscle and burn calories long after your gym session. "Ladies will not bulk up," Lovitt says. "You will maintain active tissues in your body (tissue that burns calories), which makes your body more efficient at burning fat."

Lovitt recommends mixing weight training and cardio into a circuit-type workout to lose body fat. "Mixing cardio with resistance training helps blast fat and increase your metabolic rate," Lovitt says. "Essentially, you're burning body fat while maintaining muscle mass, which allows you to shred the extra pounds and see definition much more quickly." So lift -- and lift heavy.

While many are inclined to load up on carbs before they workout, Lovitt says this is ineffective for losing body fat. "Abstain from eating carbohydrates an hour before activity, especially high glycemic carbohydrates, as carbs release insulin," Lovitt says. "Once insulin is present in your body, your body can no longer utilize body fat as its primary energy source because the insulin suppresses the enzyme required to burn body fat." If you must eat something before a workout, Lovitt recommends picking a protein-based snack.

While you should skip the carbs before your workout, post-exercise is a different story. When you're trying to lose body fat, it is essential to have a snack with a blend of carbs and protein after your workout, advises Lovitt. "You want to snack within a 20- to 30-minute window post-workout," Lovitt says. "This helps bring your cortisol levels back to normal and keeps body fat away from your midsection." Reaching for snacks like rice cakes and peanut butter are great options.