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17 Day Diet – Everything You Need To Know

Published: 20th Jul 2019. Last updated: 26th July 2019.

Shaun Ward MSc ANutr

Staff Writer


The 17 Day Diet is a popular weight loss program created by Dr Mike Moreno, who is part of the board of the American Academy of Family Physicians.

He claims that the diet has helped millions of people safely lose weight in short periods of time (even up to 12 pounds in just 17 days!).

The mechanisms behind doing so are apparently by “revving up” ones fat-burning metabolism and forming healthy eating behaviors.

According to Dr Mike Moreno, this is achieved by constantly cycling through different daily calorie intakes and food combinations every 17 days (4 cycles).

For unknown reasons, this is claimed to force the body to stay in a fat-burning state by “keeping the body guessing”.

What Is The 17 Day Diet?

The 17 day diet is split into 4 distinct phases. The first 3 phases last 17 days each, whereas the last cycle is meant to be followed for life. The 4 phases are:

Phase 1 – Accelerate

This phase is meant to induce rapid weight loss. The main guidelines for this phase are:

  • Significantly lower the consumption of dietary fat and carbohydrates (especially added sugar) whilst focusing on low-calorie foods that are more well-suited to contribute to a healthy weight loss diet
  • Increase protein intake to reduce hunger

Other guidelines to follow include:

  • Although most carbohydrate-based foods are banned, fruits are allowed before 2pm
  • Only consume skinless poultry
  • Avoid alcohol and sugar to improve digestion
  • Consume 2 probiotic foods daily to promote digestive health
  • Eat slowly and chew thoroughly
  • Drink 8 glasses of water each day
  • Exercise at a moderate intensity for at least 15 minutes per day

Based on these guidelines, this phase of the diet is going to be based around:

  • Fish
  • Poultry
  • Non-starchy vegetables
  • Low-sugar fruits
  • Probiotic foods
  • Oils (Olive and flaxseed oil)
  • Low-calorie condiments

Phase 2 – Activate

The phase is designed to boost the metabolism, and alternates between low-calorie and high-calorie days.

On low-calorie days, users are advised to stick to the guidelines of the Accelerate cycle in phase 1.

However, on high-calorie days, individuals can add 2 servings of starch-based carbohydrates such as legumes, grains, tubers and root vegetables (following the other phase 1 guidelines outside of this).

In other words, for 17 days you alternate between Accelerate and Activate days.

On Activate days the foods are usually based around:

  • Shellfish
  • Lean cuts of beef, pork, lamb, veal
  • Grains
  • Legumes
  • Starchy vegetables

Phase 3 – Achieve

This phase aims to achieve more steady weight loss by controlling portion sizes and introducing exercise such as the 17 Minute Spot Reduction Workout.

In general, the diet is similar to the Activate days of phase 2, however the selection of carbohydrate sources is diversified to incorporate breads, pastas, high-fiber cereals, and fresh fruits and vegetable.

In addition, one glass of alcohol per day is an optional inclusion.

As the amount of food and calories is going to be higher during this phase, it is also recommended to proportionally increase the amount of aerobic exercise from 17 minutes to ~45 minutes per day.

On Achieve days the foods are usually based around:

  • Meats
  • Breads
  • High-fiber cereals
  • Pasta and noodles
  • Vegetables
  • Fruits
  • Low-calorie cheeses
  • Milks
  • Oils
  • Raw nuts or seeds
  • Avocado
  • Optional snacks (frozen fruit bar, granola bars, light microwave popcorn)

Phase 4 – Arrive

This phase is meant to be more of a long-term solution and sustain the results that have been achieved in prior phases.

It relies on the fact that people have learnt healthy eating habits from these phases and translate them into better habits going forward.

On this phase, individuals can choose to follow any of the daily guidelines for the first 3 phases (Accelerate, Activate, Achieve) from Monday breakfast to Friday lunch.

However, people are given more flexibility on weekends, and from Friday dinner through to Sunday dinner some “treat foods” can be included in moderation. In addition, up to 2 alcoholic beverages per day can be enjoyed over the weekend.

However, no more than 3 of these types of “cheat” meals should be eaten in 1 weekend.

Does The 17 Day Diet Work?

The 17 Day Diet will cause rapid weight in most people as it severely restricts daily calorie intake, and indirectly puts someone in a calorie deficit (burning more calories than being eaten per day).

After all, the only way to lose weight is to consume less calories than are being expended on a continuous basis [1].

In fact, fat loss depends on energy deficit only, independently of the method for weight loss [2].

In our humble opinion, the only problem is that there are other diets for weight loss out there which have the exact same benefits and are far simpler to follow.

The 17 Day Diet Negatives

Unsubstantiated Claims

Although the diet achieves its main goal by aiding weight loss, it makes a variety of scientific claims on the reasons for doing so that are simply unsupported by valid evidence.

This can easily confuse the person on the diet, and despite the end result being the same, it is important to correctly inform people on the basic mechanisms behind biological changes.

The major scientific errors they make in this regard are:

  • Frequently changing food groups and daily calorie intakes confuses and boosts the metabolism – Not only is this claim not backed by a single research paper, but it does not make sense from a basic biological standpoint. There are no cells, enzymes, or metabolic processes, that can possibly be “confused” by dietary intake. They simply recognize and respond to nutrients in a structured and controlled manner based on their specific functions.
  • Avoid carbohydrates after 2pm as they are harder for the body to burn later in the day – The principle behind lowering daily carbohydrate intakes is well justified, and it is typically best to consume them around a given exercise session. However, there is no biological reason why carbohydrates in the morning are superior. The amount of fat lost over the course of a 24 hour period is solely determined on the net calorie balance across the entirety of the day, and not by acute periods within the day.

It Seems Excessively Complex

In general, the diet does a good job at promoting healthy eating behaviors and lowering calorie intakes.

However, when compared to similar diets that also effectively achieve this, the 17 day diet is overly complicated that may be hard for people to stick too.

The frequent changes to what is allowed and not allowed is unnecessary, and stops people from developing consistent dietary habits which they can maintain in the long-term.

Online reviews also confirm that many people quickly get frustrated with the different rules every 2-3 weeks and end up reverting back to old habits.

Depending on the person, it may be a better idea to stick with more balanced and consistent diets that promote more sustainable eating patterns.


The 17 day diet is a weight loss program that cycles through different daily calorie intakes and food combinations every 17 days.

Overall, the diet is great for making people reduce their food consumption and focus on healthy wholefoods. People looking to lose weight and improve their current eating behaviors will likely find success with the 17 day diet.

However, the diets complex and frequently changing rules may be difficult for some people to stick too.

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