One Of The Most Aggressive Diets Out There

One Of The Most Aggressive Diets Out There

This diet is one of the quickest and most aggressive diets in cutting fat and weight. In most circles, this is seen as dangerous or poor planning, but as we know, most individuals won’t care. 

Instead of demonizing the plan, this is an article aimed at planning it out safely and with controlled constraints to provide the best results.  

The Crash Diet

This is fast - I repeat fast - approach to losing weight. Introduced by Lyle McDonald of Bodyrecomposition; Lyle has written much on dieting and fat loss and is the bulk of what will be in this article. 

In his booklet The Rapid Fat Loss Handbook, he even says in the beginning “A guide on how to lose 4-7 pounds of fat and 10-20 pounds of weight in 2 weeks.” Wow, that is aggressive and at first glance, dangerous from a trainer's POV. But let’s see what Lyle has to say. 

Disclaimer - I am not a nutritionist or dietician and all my recommendations and information come from people much smarter than I. Even Lyle states that this diet isn’t ideal or sustainable, and has the potential for dangerous outcomes including unhealthy rapid weight loss, inability to sustain a healthy habit and shock to the body for recomposing too fast. 

Why am I writing about it then? And why has Lyle written a book about it? 

It’s because individuals are going to want to lose weight rapidly regardless of what anybody says. Some studies even state that most people overestimate how much weight they want to lose and when it comes to setting goals, we can be 30%-50% overzealous in our ideal number. 

On the other hand, there are some scenarios where this may be ideal and actually be the kickstart to starting a sustainable healthy eating practice. 

Most of the weight you shed will be water weight but tissue loss will also be apparent and in large part because of the large caloric deficit this diet requires. Now let’s get into the bulk of this.

First - Determine what Body Fat % (BF%) you are. This will help you differentiate which category you’re in and how to proceed with the diet. To find out, use the chart below

Second - Calculate your lean body mass from your BF%. [ weight X BF% = LBM ]

Third - Determine the category you are based on the BMI chart

Forth - Cross-reference your LBM and how much you plan on working out (be it only anaerobic, aerobic or no weight training) to figure out how much protein you need to sustain enough energy each day. [ LBM X multiplier = g per day of protein ]

Once you have this information, you can set a healthy number for protein intake. 

  • Example: a 150lb woman with a LBM of 114lbs and 36lbs of fat (24% BF) on a weight training plan will need 171g-228g on this diet in large part because of her small stature and busy lifestyle.

All of this information is important as it will create the base on which you will compare your numbers at the end and inform you on how to feed yourself properly while maintaining the diet. 

The rest of the diet is fairly simple. It only consists of protein, vegetables and supplementation. That’s it. This is also why the diet isn’t for everybody. It works and is heavily restricted. 

Things To Avoid:

  • Starchy vegetables (because they are higher in carbohydrates.) This includes potatoes, corn, peas, beets, carrots, squash, turnips, and more
  • Grains and wheat (All of them are the main sources of carbohydrates)
  • Excess fat (lots of the fats will be provided in the proteins, condiments, and vegetables.)
  • Store-bought condiments. There are a lot of excess calories in these and they aren’t all bad but you’ll have to watch the labels. 

Things To Include:

  • Multi-vitamin
  • Fish oil
  • Magnesium
  • Sodium
  • Zinc 
  • Electrolytes
  • Lots of Water
  • Potassium 

These supplements are important because of the macro-nutrients and whole-sourced foods you’ll be cutting out. 

Other tidbits of information:

  • Have approx 3 main meals and 1-3 snacks a day to minimize binge eating.
  • Use hand measurements to determine macro sizes (i.e. 1oz of animal protein is = to about 7-8g of protein and a palm size of protein is about 3oz-4oz)
  • No need to limit your vegetable intake. Enough fibre in vegetables to satiate hunger cravings. 
  • Avoid low-fat consumer products as they tend to be full of empty calories. 

How Long Do You Go On This Diet?

This can be more of a convoluted question as it does depend on how quickly your metabolism slows down. As your body begins to strip away tissue (fat and some muscle), metabolism will slow down (for those with higher BF% it may speed up first,) then adjustments will need to be made. 

For an aggressive diet such as this, those in lower categories will probably spend less time doing the diet. Those in the higher categories can sustain it for longer. 

Making This All More Psychological Bearable 

In this program, you are also allowed free meals, refeeds, and breaks from dieting. This would tie into a long-term solution in sustaining consistent fat loss and observant eating as a habit. 

Depending, again, on which category you fall into. Your refeeds, free meals and breaks will look different. 

A full diet break is exactly as it sounds. You break away from the diet completely. A more reasonable approach to this would not be to overindulge but meet your maintenance intake which would sustain your current weight. Of course, during this time you may see a spike in weight but this is mostly water weight and is easy to cut once back on the diet. 

Breaks last 1-2 weeks. If you’re a category 3, you’re more likely to break for longer than say a category 1. These breaks provide something to aim for as well as replenish macro deficiencies, minerals, and vitamins, and stop the body from plateauing.

Free meals are also what they sound like. A meal in which you can deviate from the plan. Same ideology as a full diet break. You want to go to a maintenance intake instead of overindulging. Think of a nice steak dinner instead of an appetizer, a second appetizer, steak dinner, dessert, and then a second dessert. That’s not a meal, that is 5 meals in 1. 

This is great for weekends and events, so as not to take away from social gatherings or special holidays and to set up a reward system for dieters. 

Lastly, the refeeds are high-carbohydrate times that help replenish glycogen stores. This is especially critical for those working out on this diet. Glucose replenishing will ensure consistent energy and help prevent LBM breakdown. 


This diet is extremely aggressive and will produce results. All you have to do is be willing to maintain this over a moderate time period to get where you want.

Where you can fall into trouble are areas such as high caloric drinks, condiments, and over-consuming during refeeds and free meals. Beyond some food restrictions, the table is open for what you’re allowed to eat. 

It is important to note that food is neither good nor bad. Simply put, when you eat foods, different reactions occur in the body and you will produce different results. Macronutrients are “macro” for a reason and should be consumed daily and regularly. 

There is much more to include in regards to proper dieting and nutrition and this is only a quick exert to begin your journey. To establish something more concrete, be willing to dive into the nitty-gritty details of food and eating. If you're not ready for that, that's okay. Ask a professional and they can help you get started without having to worry about all the finer points.

Let this diet be a guide to perhaps start your health journey and get you motivated on what you’re able to accomplish in a small-time period. After which, you can begin sustaining a healthier diet with more flexible eating practices and consistent weight and aerobic training. 

For more information, please explore the website or reach out to me at for more information and help with your journey. 

Daniel Bednarski

Owner and operator of Revival Fitness.

daniel@revivalfitnessonline.com778 533 3285