Why “Diets” Fail: Part IV

The Science Corner

Part 4 – Calorie Deficit Doesn’t Mean Fat Loss

So far we have explored all of the factors that go in to the way your body changes and adapts to different relative energy intakes.

We found that – in an attempt to lose weight – it isn’t a simple matter of just dropping your calories and enjoying easy long term fat loss, as Adaptive Thermogenesis will always work to adjust your metabolism to meet your new intake. Dropping your calories by too much and / or for too long can cause these changes to work against you.

But, let’s just say you’ve done all the right things now, you are creating a sustainable calorie deficit and are working to offset the negative aspects of Adaptive Thermogenesis. This still doesn’t answer the last – and perhaps most critical question…Will you actually lose fat?


And here we come to the whole bitter irony. After navigating your way through ALLLL of the previous articles and finally finding yourself in a state where you have created a successful and sustainable negative energy balance, this doesn’t completely solve the last and most important part of the riddle.

Are you going to lose fat? Or are you going to lose muscle?

Just because you finally created a deficit, it doesn’t tell your body what to actually do with it.

  • Being in an energy deficit doesn’t automatically mean you will lose fat.
  • Being in an energy surplus doesn’t automatically mean you will gain fat.

Welcome to the world of Energy Partitioning

Creating an energy deficit is only part of the equation. You still have to give your body a reason to tap in to your fat stores.

All you’ve actually done is create an energy imbalance, a debt that needs to be repaid. It doesn’t actually tell your body WHERE you need to make up that deficit from.

(I have written an article previously in a bit more detail regarding energy partitioning here if you want to check it out later) Why “Energy In Energy Out” Doesn’t Tell You If You Will Get Fat

So…even though body fat might be YOUR first obvious choice, there are also other options your body can look at, one of which being your hard earned lean muscle tissue. And if your best interests are in maintaining your metabolism and your shape – or “tone” as often people refer to it – you definitely don’t want this to happen.

Losing weight and losing fat are two very different things. I don’t care how much weight you lose, but I do care what the composition of that loss is.

Has your PT ever told you to not focus on the scale weight, but rather the composition of your weight?

  • If you lose 1kg on the scales and it’s mostly body fat, you are winning.
  • If you lose 1kg and it’s 50:50 fat and muscle, hmmm we need to change something here, it’s not great.
  • If you lose 1kg of muscle and little to no fat, we are definitely doing something drastically wrong and need to change it.

As mentioned, as far as your body is concerned, it’s just an energy deficit, it will make up for this deficit the best way it sees fit. And, given the right (or wrong) circumstances this can work for you or against you.

As mentioned, as far as your body is concerned, it’s just an energy deficit, it will make up for this deficit the best way it sees fit. And, given the right (or wrong) circumstances this can work for you or against you.

To guarantee you are optimising the environment to strip body fat and maximise lean mass, you have to take a number of factors into consideration with regards to the type of exercise program you are on and how you construct your diet in the calorie deficit. Unfortunately both of these areas are too large to go in to detail in here, but if you want to read more about the different factors that go in to how your body controls energy partitioning, check out my fat loss series

But for now, let’s focus on a couple of the biggest key factors…

KEY IMPORTANT SCIENCY THING NUMBER 2 – Macro’s Matter More Than Calories

“Macronutrient composition may add to metabolic changes in response to overfeeding. While there were no differences in increases in EE after either carbohydrate or fat overfeeding [19], a high protein intake may have a greater effect. Hypercaloric protein-rich diets (with a protein content at 25 % of energy intake) increased FFM, TEE and REE [20•]. However, AT was not different between diets differing in protein content.” (Muller, et al, 2016)

Let’s say it one more time with feeling

There are no differences in Energy Expenditure with carbohydrate and fat overfeeding, a high protein diet may have a greater effect.

Hypercaloric protein rich diets increased fat free mass, and also increased energy expenditure.

What have I been saying repeatedly for over 15-20 years now? Not all calories are created equal. The way your body processes protein is not the same as carbohydrate which is not the same as fat.

First step when you are in an energy deficit or surplus though is…Get your protein intake right!

I won’t go in to the details of the different roles of your proteins, carbs and fats, I have covered these in detail in the past. All you need to remember, when it comes to constructing your diet, these levels are set for a reason!!

It’s not good enough for you to just count your calories each day, that tells you NOTHING!

Take home message: Count your macro’s not your calories.


“Weight loss results from a negative energy balance and changes in body composition; it is not continuous but curve-linear ending when a new steady state and, thus, a new equilibrium between energy intake and energy expenditure are reached” (Muller, et al, 2016)

We have obviously already talked about this in the previous articles, but let’s also look at it from a slightly different angle.

No diet works forever. It doesn’t matter what calorie intake you choose, your body will lose weight ONLY until a new steady state is reached. If you went too hard too quickly, inevitably your results will stall. If you’re already eating next to nothing, then there is nothing more left to lose.

Your diet needs to be a shifting, changing and fluid process that is based on how your body is changing and adapting. Again, this is the reason why consistent assessment is key as it tells you what is going on and how your body is adapting.

Refeeds and Diet Breaks

“When recovering from starvation, people spontaneously overeat; body weight and fat mass increase. Weight regain may be forced by persistence of the starvation-induced suppression of thermogenesis. However, during a controlled caloric restriction-refeeding cycle in healthy lean men, mass-independent decreases in REE reversed within 2 weeks of refeeding” (Muller et al, 2016)

Yes, I’ve said this about 7 times in previous articles already, but it again highlights why these factors are so important.

The reason your diet fails is because you are focusing on the wrong things

You cut back on calories as the only means to try and lose weight

You essentially starve yourself for a period doing something that isn’t sustainable and when you come off it, you WILL spontaneously overeat to compensate for it.

This can be offset if you did it correctly from the beginning with a controlled restriction – refeeding cycle, reversing these even within just 2 weeks!

Want again to know why we run repeated 6 week challenges throughout the year with timed planned breaks in between them? To offset any negative effects from AT to ensure your success is sustainable and long term.


For years I have told my clients it’s easy to lose weight. All you have to do is create an energy deficit. It’s not so easy to just lose body fat.

And it’s not so easy to KEEP just losing the body fat over the long term.

As you can see, you have numerous hurdles to overcome. You have to create an energy deficit, but, due to AT you can see this isn’t as simple as just eating less.

Not only that, you have to create an environment that is conducive for this to come from fat loss.

Creating the optimal fat loss environment in a deficit is more about manipulating your hormonal environment which is completed through careful planning of both your exercise routine and your macronutrient intake.

  • Diet isn’t just about creating an energy deficit. Even though you still have to create some sort of negative energy balance, you must do this while also creating a state that is conducive for this to come from fat loss.
  • It requires carefully calculated ways to reaching this energy deficit. But also the right blend and balance of your Protein, Carbs and Fats to optimise the fat loss environment and encourage lean mass accretion.
  • It requires you to create this negative energy deficit in the right balance where it is enough for your body to care, but not too much that your body overcompensates with a suboptimal Adaptative Thermogenesis response.
  • It also requires planned refeeds and diet breaks to offset the long term effects of dropping calories and ensure long term success

Sad to say, again, after all of that, it really does just come back to Diet and Exercise. It’s as simple as that and yet so much more complicated than that.


Müller MJ, Enderle J, Bosy-Westphal A. Changes in Energy Expenditure with Weight Gain and Weight Loss in Humans. Curr Obes Rep. 2016;5(4):413-423. doi:10.1007/s13679-016-0237-4