3-Week Diet by Brian Flatt: Does It Work?

The 3 Week Diet is a weight-loss program that combines caloric deficit with intermittent fasting, limited carb intake, exercise regimen, and supplementation.

3 Week Diet by Brian Flatt

The road to achieving your dream physique can be daunting and stressful. With a surplus of online information related to dieting and weight loss, it can be hard to distinguish the actual facts from the myths. Multiple diet plans are constantly being introduced by fitness gurus throughout the years. A specific example is The 3 Week Diet, a weight-loss program designed by Brian Flatt, a personal trainer and nutrition coach. Granted, the first question that everyone asks about every diet plan is: Does it really work? In this article, we’ll provide a detailed review of The 3 Week Diet and give a concluding verdict.

3-Week Diet by Brian Flatt

The 3 Week Diet is available in a PDF document composed of 96 pages. According to a review by web writer Mike Dan, the program is believed to help users shed approximately 10, 15 or 20 pounds of body fat within 21 days. Brian Flatt claims that he developed this diet plan while taking into account numerous scientific facts and clinical evidences. He also asserts that the program involves natural and safe weight loss techniques.

In an interview with Globe Newswire, Flatt explains that most diet plans don’t work because they fail to produce immediate results. He discusses that when an individual follows strict dietary and workout guidelines such as practicing portion control and hitting the gym every day without seeing actual changes in body weight, he or she may feel discouraged. Thus, the weight-loss program will be given up.

Brian Flatt asserts that when a dieter notices visible results, it leads to a “snowball” effect. The individual becomes more determined and engaged and the results consequently get better. Flatt states that his goal when he created The 3 Week Diet is to help dieters lose weight rapidly and avoid experiencing discouragement. In addition, Flatt says that the simple and straightforward approach encourages fitness beginners as they tend to steer away from complicated steps. His program is available for online purchase with a 60-day money-back guarantee for buyers who fail to lose weight.

According to a fitness website, The 3 Week Diet is focused on increasing intake of essential nutrients to promote proper functioning and optimal health. Anything nutritionally unnecessary is eliminated as they appear to slow or even stop the fat-burning process. The diet program also aims to address hormone imbalances that lead to weight gain or prevent weight loss.

Business Insider reports that The 3 Week Diet is explained in a step-by-step guide that tells dieters what, how much, and when to eat for boosting weight loss results. Flatt also gives recommendations for allegedly effective fat-burning exercises. The program also involves several food supplements for stimulating the burning of body fat for fuel, speeding up metabolism, and retaining muscle mass.


According to online journalist Korin Miller of the Women’s Health Magazine, The 3 Week Diet works through a combination of caloric deficit with intermittent fasting, a limited daily carb intake, exercise regimen, and supplementation.

For the price of $47, the diet plan comes in a “3 Week Diet System” that includes an introduction manual, diet manual, workout manual, and mindset and motivation manual.

Four Phases

There are four phases in The 3 Week Diet, and these are discussed in detail in Mike Dan’s review. The phases each focus on different factors. For instance, phase 1 is for liver detoxification, phase 2 requires a 24-hour fasting, phase 3 aims for fat fast, and phase 4 involves your basal metabolic rate (BMR).

Phase 1

This is a seven-day period that focuses on cleansing the liver—the body’s main fat pumping organ. The 3 Week Diet recommends several vitamin pills or supplements to help with liver detoxification and increase the body’s sensitivity to the hormone insulin. In this phase, your diet will focus on 17 vegetables and 6 protein sources.

Phase 2

The second phase requires you to fast for 24 hours. This fasting period begins from your last meal on the seventh day until the eighth day of the program. For your dinner on the eighth day, you’re allowed to eat whatever you want but you still have to limit carb consumption through portion control.

Phase 3

The third phrase is called the “fat fast” technique and starts from the ninth to the eleventh day. It focuses on melting stubborn excess body fat, targeting the mid-section and hip region. During the fat fast period, your liver will be converting fat into fuel for your daily bodily functions.

Phase 4

The last phase begins on day 12 and ends at day 21—a total of nine days. Your caloric intake will be based on an equation involving your BMR and weight loss goals. BMR pertains to the rate of your energy expenditure for performing vital bodily functions as compared to the total number of calories you’re taking in every day.


Julie Upton, a registered dietician states that the website doesn’t offer adequate information in its promotion of The 3 Week Diet. In fact, you’ll have to pay first before you receive a detailed explanation of how the diet works. Upton asserts that this fact makes The 3 Week Diet inadvisable for purchase. Moreover, she explains that losing a significant amount of body weight in three weeks will require a drastically low-calorie intake and necessitate an intense exercise routine. She claims that an extreme caloric deficit also makes you lose muscles, thus, she calls the promise of muscle mass retention a “bogus”.

Registered dietician and author Beth Warren states that although weight loss may seem immediate, it’s not permanent because the lack of carb storage only results in loss of water weight. It’s also medically considered unsafe to lose over 20 pounds of weight in three weeks.

Experts agree that a healthy weight-loss rate is 1 to 2 pounds a week, and losing more than this is unsafe and too rapid. Ryan Raman, a New Zealand-based expert in nutrition and dietetics reports that rapid weight loss can lead to adverse effects such as lower metabolism, increased risk of gallstones, and nutrient deficiencies.

Key Takeaway

Any observed results triggered by The 3 Week Diet are most likely temporary. The diet plan is also generally unsustainable in the long run and may pose some health risks.

You also have to take into consideration your individual daily calorie requirement, especially since The 3 Week Diet works primarily on caloric deficits. If you have health concerns, it’s even more important that you consult a medical professional before starting any kind of diet plan.

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