In today’s world, it seems like there is a new diet or exercise trend every week. Paleo, keto, CrossFit – it gets confusing after a while. The ones that are fads fade quickly if they aren’t effective, while others stick around. The Three Week Diet is a good example of an enduring trend.

The plan was first created by fitness expert Brian Flatt in 2015. Since then, it has been reviewed by a number of professional instructors and dieticians, such as the ASCVS, and many of them have decided that the hype is well-founded.

Flatt studied a number of methods known to be effective already and designed a condensed regimen that combined key elements of different diet plans. This includes fasting, strict meal planning, and intense exercise.

The problem that many people encounter with these diet plans is struggling to keep it going for months or years after starting strong. The Three Week Diet aims to give tangible results in a more manageable time frame.

It is divided into four phases, each lasting a different number of days and consisting of different routines. Here is a quick look at those phases and how the Three Week Diet works.

Phase One: The Super Diet

Many people who have tried this diet agree: the first part is the hardest. But that could be considered a good thing. Think about it: whenever we start a new diet or exercise routine, our motivation is the highest those first couple of days. Why not use that additional drive to accomplish the tough stuff and get it out of the way?

Phase one lasts seven to nine days and includes a rigid diet plan that is more of a crash-course than a long-term regimen. The brief duration of this phase makes it all the more important to stick to the 3 meal a day plan as closely as possible. The purpose of this phase is to cut out processed foods, cleanse the body and remove toxins.

The diet allows for some vegetables to be eaten freely, so if snacking on celery is your thing then you’re in luck. Beyond a few veggies, it restricts not only what you can eat but how you can prepare it.

It also includes an exercise regimen, to get you acquainted with your workout for the duration of the three weeks. Strict adherence to that and the meal plan will allow you to shed a few pounds right away in those first nine days.

Phase Two: The All-Day Fast

After eating regularly for those nine days, phase two can be a jolt to your system. It is only one day, but it is an all-day fast.

The science behind fasting has been studied more extensively in recent years with its inclusion in many diet plans. The reality is that people have known the benefits of intermittent fasting for thousands of years, and it is practiced in many cultures around the world.

All that being said, this one day fast, after nine days of intensely monitoring what you put into your body and your energy output, can be tough. If you’re struggling to get through it, it’s ok to reach for raw celery or a cup of herbal tea.

Phase Three: Counting Calories

This is where the math kicks in. Phase three lasts three or four days and is similar to the first phase, but it allows you to eat more of what you want while shifting your focus to caloric intake.

Over these four days, you develop a diet plan based on your individual health and habits. This allows you to develop a routine for yourself that you can maintain for the future.

Phase Four: Burn Baby Burn

Phase four lasts for the remainder of the three weeks and is designed to help you learn how to keep the weight off long term.

At first, you may have to go as far as carefully measuring out portions when preparing your meals, but the important thing to keep in mind is that you want to burn more calories through exercise each day than you are taking in.

It also helps you calculate how many calories you burn at rest so that you know exactly what you need to make up for in exercise.


As with any new diet regiment, it is recommended that you consult your doctor to ensure it is a good fit for you.