When registered dietitian and nutritionist Edward Harris, MSc, needed to lose five pounds rapidly to prepare for a fitness exam, he knew he was facing a tough challenge: He had to develop a week-long diet plan that would melt fat without depriving his body of nutrients or energy. It had to be simple, easy to follow, and suitable even for those with a very busy lifestyle.

Drawing on his knowledge and training, Harris came up with a diet plan that curbed cravings while reducing his caloric intake dramatically enough that he met his weight loss goal. It required no gimmicks, no expensive supplements, and no diet pills—just healthy, fresh whole foods that you can find at any supermarket.

The secret Harris discovered is this: If you “cycle” between consuming mostly fresh fruit and vegetables on some days, then add in more carbohydrates on other days (within a six day period), you can avoid feeling deprived (and therefore avoid the temptation to cheat).

This is because carbohydrate-rich foods trigger the release of the “happiness hormone” serotonin, which in turn creates feelings of satiety. Carbohydrates also provide us with the “short term” energy we need to accomplish immediate tasks. By consuming them in moderation while dieting, we can avoid the dreaded symptoms of fatigue and irritability that accompany most rapid weight loss plans.

The diet plan outlined below builds on Harris’s original concepts via the addition of healthy fats and protein for more lasting energy and feelings of fullness. To compensate for the additional calories, however, you’ll need to do some exercise.

You can choose from either: One 45 minute walk each day, a 30 minute aerobic routine at least 5 days per week, or a daily 15 minute HIIT session, depending on whether you prefer low-impact or high-impact exercise. You’ll also need to be extremely vigilant about avoiding liquid calories. Drink only water or sugar-free tea or coffee; avoid sugary juices, pop, and alcoholic beverages while using this plan.

The Simple 6 Day Plan for Quick Weight Loss

Day One: Eat only low-sugar fruits during the day. Avoid high-sugar choices like bananas or pears and opt for apples, citrus fruits, and pomegranates instead. If you find that you’re hungry at the end of the day, top half an apple (sliced) with two tablespoons of peanut butter.

Day Two: Boil one potato; cut it in half. Eat the first half in the morning, topped with one teaspoon of sour cream and salt and pepper to taste. Throughout the day, snack on as many vegetables as you want—there are no limits on how much you can eat, as long as you choose raw, fresh vegetables.

We suggest choosing high-fiber veggies like celery to promote feelings of fullness. If you find eating plain vegetables difficult to enjoy, you may pair them with either one tablespoon of hummus or one tablespoon of low-fat dressing. For dinner, enjoy the rest of the boiled potato (topped with one teaspoon of sour cream and salt and pepper to taste) and half a sliced avocado.

Day Three: Combine as many low-sugar fruits and vegetables as you like on day three, but skip the starches (i.e., no potatoes, rice, or bread of any kind). Add two tablespoons of pumpkin seeds as a mid-day snack, and enjoy one snack-size portion of plain Greek yogurt in the evening.

Day Four: On day four, you’ll need to add more calories and sugar back into your diet to avoid feelings of deprivation and fatigue. Start the day with a glass of milk and two bananas topped with two tablespoons of peanut butter and sprinkled with one tablespoon of chia seeds. Snack on another two bananas throughout the day and end the evening with a bowl of vegetable soup and one slice of whole-wheat toast.

Day Five: Pair one serving (1/2 of a cup, cooked) of plain, boiled rice with as many vegetables as you want (eaten throughout the day). Have a sliced apple topped with two tablespoons of peanut butter for dessert.

Day Six: Eat three portions of vegetable soup throughout the day. For a side dish, prepare one serving (1/2 of a cup, cooked) of plain boiled rice blended with half a diced avocado and topped with one teaspoon of olive oil, plus lemon juice, salt, and pepper, to taste.

On day seven, you’ll be allowed to cheat and indulge in some of the treats you may have missed during the preceding days. Start with a basic meal plan of one serving (1/2 of a cup, cooked) of plain boiled rice, and help yourself to an unlimited amount of vegetable soup and green salad.

Eat these items during the day, before any treats, in order to avoid over-indulging throughout the day. In the evening, add up to 500 calories’ worth of treats, such as one large slice of cake, two glasses of wine or beer, one serving of ice cream or French fries, etc. What you choose to be your treat (or treats) is up to you, as long as you do your best to avoid exceeding the 500 calorie limit.

Taking The Next Step

How you implement this plan in the weeks to come is ultimately up to you. Some people repeat the six day plan for several weeks to maximize their weight loss results, while others follow the plan for one week out of the month, several months in a row. (This will produce more gradual weight loss, and you’ll need to eat sensibly during the other three weeks of the month, too. We recommend adhering to a 1200-calorie-per-day plan for the rest of the month if you do this.)

Not everyone will lose a full ten pounds in just one week using this six-day plan, but almost everyone will lose at least 5-7 pounds. To avoid frustration (and the subsequent temptation to cheat), Harris strongly recommended that followers of this diet put their scale away for the entire week.

That’s right—You shouldn’t weigh yourself at all until day 7. Personally, we suggest weighing yourself on the morning of day 7; when you see how much weight you’ve lost over the prior six days, you’ll be less likely to go overboard on your “cheat day.”

If you follow this diet for two to three weeks and don’t see any significant weight loss, you should absolutely book an appointment with your doctor to rule out a possible medical condition. From Harris’s observations over the years, the only people this diet doesn’t work for are people with thyroid problems, hormonal issues, and people who are taking medications that promote weight gain. If you have any of these problems, you’ll need get them treated before any diet will work properly for you. Good luck!