Rapid Fat Loss Guide

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I went back and forth on if I wanted to make a blog titled “Rapid Fat Loss” or not. It can give the wrong idea that I am promoting rapid fat loss.

However, after thinking it through I realized people are going to try protocols that call for quick weight/fat loss anyway, so I might as well try to inform them on how to do it safely and properly. 

Before we dive into the nitty gritty stuff, it’s important to go over a few things. 

  1. What is rapid fat loss?
  2. Why it may or may not be a good idea
  3. Who it’s for and not for. 

What is Rapid Fat Loss?

For most people a good weekly decrease in weight is around .5 to .75% of their bodyweight per week. And this is what I highly recommend for MOST clients and people in general. 

For example, if you are 170lbs that would be around .8 to 1.2 lbs lost per week, which is solid. By losing this amount you are somewhat “protecting” yourself from some of the nasty side effects that can potentially come with dieting and trying to lose fat. We will go over those in a minute. 

*Side note: Weight loss is just any amount of body weight lost, whereas fat loss is body fat. Your goal should usually always be to lose body fat, not just any bodyweight. We want to keep as much lean mass as possible. In saying that, seeing your weight go down is a GREAT indicator of fat loss, especially if you follow the other tips I go over in a bit. 

For the sake of this blog, we are going to call rapid fat loss .8-1.1% of bodyweight lost per week. So for a 170lb person that is 1.3 to 1.9lbs per week. 

To find this amount for your weight you would do: 170lbs x .0008. 

Lets do another example, lets say you are 210lbs. For them .8 to 1.1% per week is 1.7 to 2.3lbs per week. 

One more example, if you are 250lbs .8 to 1.1% of your bodyweight per week would equal 2 to 2.8lbs per week. 

You are probably thinking, “wait 1.5 to 3lbs per week? I thought this was going to be some crazy amount of weight loss per week”. 

But the truth is going much higher than this comes with a TON of negative consequences (we will get into this in a minute). 

And again, remember our goal is NOT just weight loss, its FAT loss. Meaning you want to maintain as much lean body mass as possible, oh and you probably don’t want to feel like crap all the time. 

So moving forward rapid fat loss is considered losing .8 to 1.1% of your bodyweight per week. 

Why It May or May Not Be a Good Idea

I want to start with the bad ideas first so hopefully if you are on the fence you decide it isn’t for you. When it comes to your health and fitness taking the safer route is NEVER a bad idea. 

So the bad ideas.

Anytime you push your body outside of where it’s comfortable it’s going to fight back. Our bodies don’t realize it’s 2020 and you can eat 3,000 calories without having to use any energy. 

This is much different than the environment we evolved with. Back then, you weren’t sure when your next meal would be, not to mention you may have to use a ton of energy to get that meal, so naturally the body wants to hold onto/store any energy you give it. 

Again, this is great for how we evolved, not so great now. 

So when you lose weight here are some consequences that come along especially the faster (more than 1.1% per week), longer, and the more weight you lose:

  • Muscle loss risk: Muscle loss can lead to increased feelings of fatigue and weakness. 
  • Decrease in training performance: Poor training= tougher to maintain muscle/increase risk of muscle loss (see above). 
  • Health: Potential vitamin and mineral deficiencies from eating a low calorie diet. 
  • Metabolism slows down/NEAT decreases: Read here for more info on what happens when you lose weight and how important NEAT is. 
  • Decreased sleep quality: Poor sleep can lead to increased hunger and cravings, making a low calorie diet tough to stick to. 
  • Increased stress hormones: Chronically high stress levels can lead to muscle loss (see above). -Increased hunger: If your hunger is always high, sticking to a lower calorie diet is going to be tough. 
  • Fatigue: The more weight you lose and the longer you do it, the more tired you will get over time. This is your body being efficient with its energy (again it doesn’t realize you can walk two feet and down 3,000 calories). 
  • Psychological issues: Dieting for fat loss is tough. It can wear you down. You have to make a lot of sacrifices. So the faster and longer it is, the more these can weigh you down. 

As you can see, there are a lot of risks that come with losing weight too quickly and for long periods of time. 

This is why with the rapid fat loss protocol you aren’t losing more than 1.1% of bodyweight per week. 

The pros do NOT outweigh the cons. Here in a bit, we will go over how to lower the risk of all of these in the diet structure portion. 

Ok now lets go over why going at it faster may be of benefit. 

  • A much quicker buy-in: In my experience working with clients, a quick initial buy-in makes your job 1000 times easier. Also for you, you are more motivated and more likely to adhere to the plan when you see it’s working. Studies show that a more rapid weight loss leads to more buy-in and can reinforce weight-loss behaviors, likely leading to better long-term weight loss outcomes  (Seimon, et al., 2019)(Nackers, et al., 2010).
  • This is very similar to the last point, but faster results are always more appealing and these are more likely to get more people initially interested in becoming healthier, which is a win for everyone. 
  • A lot of weight to lose. If you have a lot of weight to lose, going at a faster rate may be of more benefit to you than someone who doesn’t have much weight to lose. 

Essentially the pros all come down to more initial buy in, which then leads to a trickle down effect in the future. 

Who Its For and Not For.

Again I want to start with the negatives and who it isn’t for. That way you can find out sooner if this protocol is right for you or not without getting too invested. 

Who its not for:

  • Someone who is already lean. If you are already fairly lean, this protocol is NOT for you. Your risk of all of the diet side effects listed above increase the leaner you are. Its tough to put a number on this but in saying that, if you are lower than 20-22% for females and 12-14% for males, dont do it. 
  • If you have had food or diet issues in the past. Going at a quicker fat loss rate will only exacerbate those issues. 
  • If you lack basic knowledge of nutrition. Do you know what a calorie deficit is? Do you know what is considered protein? Do you know what is considered a carbohydrate? If you don’t, then this is NOT for you. 
  • If you aren’t lifting/don’t plan to lift weights, this isn’t for you. 

If you check any of the boxes above, its better to fix these issues or go to a lower weight loss per week (.5 to .75). 

On the other hand you can consider this protocol if:

  • You have higher body fat levels. Your chances of losing muscle are very LOW. As long as you are eating adequate amounts of protein your body will prioritize burning body fat. 
  • You have no issues with food or dieting in the past. Having done a fat loss diet once or twice helps. 
  • You have a solid nutrition knowledge base. You know your body well, you know what a calorie deficit is, you know what foods are considered protein etc. 
  • You are weight training at least 2-3 times per week CONSISTENTLY. 

So now you know if the rapid fat loss protocol is for you. 

Now lets get into the nitty-gritty stuff. 

Diet Structure

1. Setting up Calories

The first thing is to set up your calories. For a more in depth discussion on how to set up your macros/calories go HERE. I highly recommend reading this first. 

>Multiply your body weight by 14-16 or 16-18 if you are very active.

You can also use this calculator HERE.

Once you find your maintenance level calories (after a few weeks of monitoring your bodyweight) you then would calculate what you want your rate of loss to be. 

I recommend starting out at .8% and going from there, but ultimately you will decide on what exact number you chose. So for this blog’s sake let’s go with the high end of 1.1% using our 170lb person as an example. More on how long the diet should be in a bit. 

>Maintenance cals: 170 x 16 = 2720. Round to 2700 to make it easier. 

>170 x .011= 1.9lbs per week. To make this easier we will just round to 2lbs. 

It is said that in order to lose a pound of fat you need to burn 3,500 calories. 

So in order to lose 2lbs per week we need to burn 7000 calories.  3,500 = 1lb. 2lbs = 3,500 x 2.

700/7(days in the week)= 1,000

That comes out to a 1,000 calorie deficit per day to lose 2lbs in a week.

>So you then would take your maintenance amount and subtract 1,000 from that. 

2,700 – 1,000= 1,700. 

That’s your starting estimated calories to lose around 2lbs (1.1% of BW) if you are 170lbs. 

*Side note: It’s important to note that these numbers are ESTIMATES. You may have to adjust up or down. 

2. Setting up Macros

Next are your macros. Again, if you want a more in depth article on macros/calories I highly suggest reading THIS.

Since this is a rapid fat loss protocol, you MUST make sure you are getting adequate amounts of protein. 

For the rapid fat loss protocol, 1g to 1.5g per lb of bodyweight is recommended to maintain as much lean body mass as possible. Protein can also help lower hunger. 

Lets go in the middle and aim for a 1.2g per pound of bodyweight per week. 

>170lbs x 1.2= 204g protein. Round to 200 to make it easier. 

>200 x 4 = 800 calories. So you have 900 calories left. 

You MUST hit a minimum fat number of .3g per lb of BW so 170lbs x .3= 51g of fat, round to 50g to make it easier. 

>50 x 9 = 450 calories. 450 + 800 = 1250 so you have 450 calories left for carbs. 

>450/4= 112.5, round to 110 to make it easier. 

So here are the example macros:

  • 1700 cal
  • 200g protein
  • 110g carbohydrates
  • 50g fat

Double check your numbers: 200 x 4 = 800 + 110 x 4= 440 + 50 x 9 = 450 = 1690. Good to go. 

Tip: Go read over my article on macros if you do not know how I came up with those numbers.

3. Duration

Now that you have your macros, it’s important to figure out how long you are going to be dieting for. 

Ideally we would aim for 6-12 weeks. If you choose the higher end of percent weight loss per week, then you need to aim for a shorter duration to avoid the negative effects of dieting (listed above). 

It’s also important to lose no more than 6-10% of your overall body weight during one fat loss phase. 

>For example, a 170lb person could aim to lose around 8% of their bodyweight. 170 x .08= 13.6, round to 13.5lbs lost during the rapid fat loss protocol. 

So if you choose to lose 2lbs per week then you should look at dieting for 6-8 weeks. 

4. Calorie Adjustments

Since these calorie amounts are just estimates there is the chance that your calorie intake may not be low enough for you and the amount of weight loss you selected per week.

If you go 1 week without losing any weight then drop your calories by 5%. In our example this would be: 

>1700 calories x .05 = 85 calories to decrease. To make it easier, round to 100. 

>1,700 – 100 = 1,600. 

This would be your new calorie amount. Take your calories from carbs. 

>100/4= 20.

So you would subtract 20 carbs from your original number which would be:

>110- 20= 90. 

Updated macros based on this:

  • 1,600 calories
  • 200g protein
  • 90g carbohydrate
  • 50g fat

If you are falling under the selected weight loss per week you set out but still are losing weight, if 2 weeks go by and you are still under the target amount for the week, then decrease by 5%.

Avoid making too big of a decrease in calories. You will already be eating a fairly low calorie amount so you want to limit how much you take away. 

Make sure that before you reduce your calorie intake, your adherence is on point. 

The rapid fat loss protocol requires a high amount of adherence, which is why it isn’t for everyone. So before you drop your calories make sure you are hitting your numbers 7 out of 7 days. 

This is where having a coach can be super helpful. Sometimes we over think these things and make unnecessary changes just because you were not patient enough. We also tend to make things overcomplicated.  



You MUST lift weights during this rapid fat loss protocol to avoid losing muscle. If you only focus on cardio then you will lose muscle and this will make this protocol much tougher (see above for consequences of losing muscle). 

Aim for AT LEAST 3 days per week. Hit each muscle group 2x per week. 8-20 sets per muscle group per week. 


Proper sleep is essential during this rapid fat loss phase so you can put your body in the best position to lose body fat and maintain lean mass. Not to mention poor sleep can lead to increased hunger and cravings, which will make it tough to adhere to your diet on low calories. 

One thing I have changed my mind on is that first focusing on sleep QUALITY is better than trying to improve sleep QUANTITY. 

Here are some tips from Precision Nutrition on how to improve your sleep quality:

  • Consistency:  Keep a relatively consistent bedtime and wake time. Staying up late and sleeping in on weekends can disrupt your routine during the week.
  • Light: Keep the bedroom extremely dark, to tell the body’s light-sensitive clock that it’s time to sleep.
  • Noise: Keep the bedroom extremely quiet or use a white noise generator (such as a fan).
  • Relaxation/routine: Develop a pre-bed routine that is relaxing and familiar.  Television, work, computer use, movies and deep/stressful discussions late at night can disrupt sleep.
  • Temperature: Keep a slightly cool temperature in the room, between 66-72 F or 18-22 C.
  • Stimulants: Eliminate stimulants like caffeine/nicotine, especially later in the day.

Food Choices 

Food choices are also very important during this rapid fat loss protocol. As we discussed earlier the less you eat and the longer you diet your hunger will rise. Again, this will make adherence tough and a challenge. You can fill up on any food so long as you stay within your calorie amount, however it’s probably a good idea to stick to whole foods and limit your intake of tastier treats. Read HERE on how tastier foods can lead to increased hunger and more food being eaten.

Normally I encourage a 80/20 approach with online clients when dieting for fat loss. However, since your calorie intake is much lower during this rapid fat loss its a good idea to stick to mostly a 90/10 – 95/5 approach. 

Here are the foods you want to be eating 90-95% of the time:

Here is a sample breakdown of how your day might look meal wise:

  • I have this broken down to 4 meals because that’s where most of my clients seem to feel best, but that doesn’t mean 3, 5, or 6 meals won’t work – adherence is the biggest factor, so figure out what works best with your schedule (something you can repeat daily).

I have the example day above – if your training time changes, this can and should change. Daily calories are most important – much more than meal-timing.

Again hunger will be an issue during this protocol, here are some tips on how to decrease your hunger while on a fat loss diet:

  • Increase protein intake.
  • Spread out meals to avoid the really hungry stage.
  • Meals, not snacks.
  • Reduce liquid calories.
  • Drink fluid before meals.
  • Increase caffeine.
  • Slow down your eating.


Lastly, drinking alcohol during the rapid fat loss protocol is a no go. Even if you can make it work, it will be too tough to eat enough food to fuel your body for training and overall health. By drinking alcohol  a certain amount of your low-calorie diet will be allocated to alcohol, which is not great, not only for seeing fat loss, but it will also make adherence MUCH tougher. 

It just simply won’t work. There is no way around this. If not drinking alcohol for 6-12 weeks is a no-go for you then that is completely fine, but something you must consider. 

If you have a drink here or there during this protocol, you can potentially make it work. But just realize you are shooting yourself in the foot. 

Diet After the Diet. 

Once you finish the rapid fat loss protocol its important you step away from dieting for fat loss. You will be on the brink of all the diet fatigue side effects we discussed earlier. So it’s important you increase your calories close to where you were before you started this protocol. 

Subtract 1 from 14-16 and find your new maintenance level calories. For example, if you took 16 to find your maintenance in the beginning, then multiply your new body weight by 15 and that’s where you will start with the diet after the diet. 

You may see a slight increase in weight, but don’t stress this as it is simply water weight and more food in your stomach from increasing your food intake back to normal ranges. 

For more information on how to manage weight loss long term read this blog HERE

I hope all of this information was helpful and will help you lean out at a fairly rapid pace. 

In saying that, if you want to give this a try and aren’t confident in your ability to run it on your own then fill out the link HERE and let’s get you started. 


Seimon, R. V., Wild-Taylor, A. L., Keating, S. E., McClintock, S., Harper, C., Gibson, A. A., Johnson, N. A., Fernando, H. A., Markovic, T. P., Center, J. R., Franklin, J., Liu, P. Y., Grieve, S. M., Lagopoulos, J., Caterson, I. D., Byrne, N. M., & Sainsbury, A. (2019). Effect of Weight Loss via Severe vs Moderate Energy Restriction on Lean Mass and Body Composition Among Postmenopausal Women With Obesity: The TEMPO Diet Randomized Clinical Trial. JAMA network open, 2(10), e1913733. https://doi.org/10.1001/jamanetworkopen.2019.13733

Nackers, L. M., Ross, K. M., & Perri, M. G. (2010). The association between rate of initial weight loss and long-term success in obesity treatment: does slow and steady win the race?. International journal of behavioral medicine, 17(3), 161–167. https://doi.org/10.1007/s12529-010-9092-y

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