Fad diets and juice cleanses for quick weight loss often lack essential nutrients that your body needs to function. Rather than shocking your body with methods that may not be scientifically researched, follow these seven essential rules to start rapidly burning fat the healthy way.

Eliminate carbs

To achieve rapid weight loss, you’ll have to alter your diet. Fat loss has always been about calories in vs. calories out. For ultimate fat loss in five days, planning ahead is best. Slowly start dropping carbs from your diet a few weeks prior to your five-day “cut” until you’re eating fewer than 50g a day. Then, the real weight loss will happen during those days where you’re at less than 50g of carbs.

For example, if you weigh 185lbs and typically eat 400g of carbs a day, try consuming 300g a day for a week, then 200g a day the next week, then 100g the next, and finally less than 50g for five days.

Carbs like pastas, rice, breads, potatoes, etc. tend to be calorie-dense, making it harder for you to rapidly lose weight. On top of that, they bind to more water than protein or fats—within days, guys will often lose a few pounds because of the drop in water weight.

Do intermittent fasting

Intermittent fasting increases the duration between meal times—the easiest way to do this is to skip breakfast. If your last meal the previous night was at 6 p.m., by waiting until noon the next day for your first meal, you’ll have fasted for 18 hours.

This 2005 study from the American Journal of Clinical Nutrition found that intermittent fasting increased fat oxidation, which promoted more fat loss. Fasting combined with exercise further increases your insulin sensitivity, according this 2010 Journal of Physiology study, which helps your body better partition nutrients between fat and muscle.

Skip breakfast for the next few days, and eat your first healthy meal of the day in the afternoon.

Do high-intensity interval training

If you want to burn fat quickly, you need to dial up your cardio another notch. A recent Medicine & Science in Sports & Exercise study found that HIIT improves VO2 max, and burns more calories compared to continuous aerobic training. Furthermore, this 2013 Journal of Strength and Conditioning Research study found that four weeks of HIIT rowing burned significantly more fat than traditional rowing.

Rather than spending hours on the treadmill, however, focus on doing fat-torching circuits that target your entire body. For example, create a circuit with goblet squats, dumbbell/barbell rows, push presses, and pushups, do them each for 30 seconds, and rest for 30 more seconds before moving to the next on. As a finisher, use an Airdyne bike, rowing machine, prowler, etc., and do max-effort intervals, 15 seconds on, 15 seconds off.

Take fish oil

Fish oil can help you burn more fat with the diet and exercise plan you’re already doing.

A 2010 study in the Journal of the International Society of Sports Nutrition found that fish oil supplementation led to an extra drop in fat mass, and an increase in muscle gain. If your goal is fat loss in five days, boost your fish oil intake to 1g of fish oil per 1% of body fat. So, if you’re at 16% body fat, take 16g of fish oil, spread throughout the day.

Drink cold water

Drinking plenty of water will keep you hydrated so that you perform at optimal levels. Even a slight amount of dehydration can wreck your ability in the gym, and reduce your metabolism as your body tries to conserve fluids.

But the act of drinking water by itself can help speed up your fat loss. In a 2003 Journal of Clinical Endocrinology and Metabolism study, researchers found that drinking two cups of cold water increased metabolism by 30% within 40 minutes.

Eat more lean protein

Protein is crucial for rapid fat loss. One, it keeps you feeling full, which prevents overeating and needless snacking. Two, it boosts your calorie burn throughout the day because it takes more energy to digest compared to carbs or fat. Three, it prevents any muscle loss that might happen during a caloric deficit.

Eat at least 1g of protein per pound of bodyweight, and get your protein from whole sources like lean meats, nuts, eggs, and quality protein powders.

Try safe supplements

Fat-burners are over-the-counter supplements that typically blend different kinds of herbs and stimulants to raise your core temperature, which can help you burn more calories at rest and during exercise, or suppress your appetite.

Common ingredients in fat-burners that help you burn more calories include green tea extract, caffeine, synephrine, capsicum, raspberry ketones, and garcinia cambogia.

Synephrine is a substance found in a variety of citrus foods such as mandarin and clementines. Recent research suggests that it’s safe for the heart, and may increase resting metabolic rate. Capsicum, a plant known for its spicy seeds and fruits, is generally used for pain relief. However, this 2011 Chemical Senses review suggests that intentional consumption may benefit weight loss. Caffeine and garcinia cambogia act as appetite suppressants, which keep portions small and junk food cravings at bay.

Fat-burners can increase your metabolism, give you more energy, suppress hunger, and increase your core temperature so you indirectly burn more calories. However, watch out for side effects of these ingredients, and be sure to not combine them with other stimulants or medications.