What are the fundamentals of fat loss? How does fat loss occur?

Fat loss and weight loss are terms often used interchangeably but mean very different things. Because the overall weight of the human body is made up of many elements, weight loss can be water loss, muscle loss, faecal matter leaving the body, and glycogen (stored sugared) utilised as fat loss. 

Fat loss occurs when the adipose tissue is used as energy. This type of fat is called triglycerides and is made up of carbon, hydrogen and oxygen. When broken down and used as energy, we breathe out the carbon atoms as carbon dioxide. A third of which occurs as we sleep.

Most of the fat used/burned by the body occurs during normal day-to-day activity and, as mentioned above, during sleep. Some extra fat can be used during exercise, but it’s not an efficient energy source.

The body will start using sorted fats when the overall daily activity exceeds the energy consumed. In this situation, the body requires more energy to fuel activity and metabolic function, so it turns to stored fuel. 

But this delicate balance pushes activity far too high and consumes too little energy (calories). The body can use stored proteins (muscle) and stored sugars glycogen. 

So you want a sensible reduction in energy consumed and consistently elevated activity, not crazy months of flogging your body to bits. 

As mentioned, the majority of fat is burned during rest, NOT activity, so nutrition / caloric reduction is the smarter place to put your focus. 

What factors influence or limit someone’s ability to lose fat?

This is where it gets a bit confusing.

Genetics can affect someone’s ability to regulate hunger and satiety and their awareness of foods around them. The gut microbiome can affect how much energy is extracted from food and food cravings and preferences. Dietary history can affect someone’s resting metabolic rate. A history of over-restricted eating will have created some adaptations to lower energy intake where metabolic activity is downregulated. This is called adaptive thermogenesis. Note: this is always overstated in the media and is usually not a large factor.

Too much exercise activity can cause a few issues. The body will either increase hunger to create homeostasis with energy or slow down other activities, such as fidgeting cognitive function and down-regulating overall movement. This is known as the scientific principle of the constrained energy model. 

Age or, more importantly, age-related decreases in muscle mass (sarcopenia). Muscle mass has a high metabolic demand, a.k .a, and muscles require more energy at rest to sustain it. 

Systemically elevated stress levels. Constantly high cortisol levels keep the body in “fight or flight” mode. As mentioned, the body utilises most fat for fuel at rest. An inability to tap into a rested state makes “fat burning” harder.

Exercise has the smallest impact on someone’s ability to lose fat – can you explain why this is and the factors that influence TDEE?

The total energy used daily is called TDEE – Total Daily Energy Expenditure. It is broken down into four parts:

• 70% –  Resting Metabolic Rate (RMR) is the energy our organs use to keep us alive. It is worth noting that the more muscle mass you have, the higher this number will be. 
• 10% – Thermic Effect of Feeding (TEF). This is the energy it takes to break down and digest food.
• 15% – Non-Exercise Activity Thermogenesis (NEAT) is the energy we use daily moving around. This does not include exercise. Think of this as more walking the stairs, making a cup of coffee or simply sitting and working at your computer. 
• 5% – Exercise Activity Thermogenesis (EAT): this is purposeful bouts of activity like going for a run, yoga, weight training, etc. 

As you can see, exercise is only a little of our energy use. So, focusing all your effort here means you’re focusing on the smallest part of the equation. You’re better off just trying to be active and walk daily versus going hell for leather in a spin class. 

Note: activity monitors (Apple Watch, Fitbit, Garmin, My Zone, Whoop, etc.) are between 13-65% inaccurate for estimating calories burned. We simply use less energy when working out. 

Why is walking important for well-being and those wanting to lose fat?

This is where the industry has been lying to you. In 2007, a systematic review concluded that exercise has little to no effect on someone’s ability to lose weight, and we have had countless more studies to back this up. We’ve known this for over a decade, yet every gym and fitness influencer chooses to ignore it or is oblivious to it. Exercise is amazing for many things, but it’s not a big part of the overall picture for weight loss. 

However, certain forms of exercise can be very beneficial for fat loss. First, I mentioned that muscle has a higher metabolic activity, so adding some muscle to your frame can be an excellent way to “boost your metabolism”. I also mentioned that high stress can make fat loss harder, so forms of training that help promote recovery and rest can also be helpful, such as yoga, breathwork, zone 2 cardio or just a walk in nature. 

Cardiovascular exercise helps your body switch to using different fuel sources internally, which can help regulate oxygen consumption and manage blood glucose. 

These indirect things can help people long-term, especially when looking to sustain their body weight after losing some fat.

You’ll have seen the most significant element of TDEE was NEAT. So going for a walk every day or every other day not only helps promote this, but there are huge mental health benefits to walking more. Also, walking is much less likely to impact hunger, which I’ve already stated is your body’s natural response to doing too much/hard exercise. 

Why is resistance training important for well-being and those wanting to lose fat?

Resistance training is a really smart move for anyone looking to lose weight. Not because it burns a lot of energy but because it will place a large recovery demand on the body. Your body will repair damaged tissues for 1-3 days after training. This uses energy – not loads, but the focus is the long game, and every little helps. As mentioned, the leaner your muscles are, the more energy you burn at rest. Once again, I don’t want to overstate this and say you get a huge increase, but again, the focus is on maintaining your body weight after losing some fat. So this really helps. Plus, weight training, especially for women, has been shown to help improve bone mineral density, tendon strength, and thickness, as well as help regulate hormones. 

Why is cardio important for well-being and those who want to lose fat?

We need to change the narrative on cardio. Yes, cardio will use more energy per unit of time than any other exercise activity. Still, we’ve already seen that it’s focussing on 5% of the energy we use on average daily, so it’s not a primary driver. But cardio is amazing for many other reasons. VO2 max – is your body’s maximum ability to absorb and use oxygen. The higher your VO2 max, the more efficient you use energy. You have already heard that we breathe out carbon dioxide as we use stored fat. So, having better cardio fitness means we’re more efficient from a respiratory standpoint. And there is a direct correlation between VO2 max and longevity/lifespan. Having a better aerobic capacity means you can carry out day-to-day takes with more ease, and once again, seeing as most of the fat we use is at rest, keeping your body in a somewhat rested state as you garden and play with your kids is advantageous. 

Are there any other types of exercise for fat loss or even things to avoid?

All exercise is good, but I really want to pull the conversation about exercise and fat loss apart so we don’t “train to lose fat”. We train to be more efficient, healthy, and optimal human beings. 

That being said, I’m a big fan of recovery modalities such as yoga, walking, breathwork and anything that promotes relaxation and sleep, especially for anyone who is generally very stressed. 

Things to avoid. Personally, I’m not a huge fan of circuit-based HIIT classes. These are often performed with poor technique and are often in a high-stress environment. Do HIIT on a bike or rower, which is where it’s more effective. The industry has butchered HIIT training into crazy circuits with burpees and box jumps. These are fine if you like them, but that’s not what HIIT really is, and that’s not an effective way to train. Lift weights and get stronger. Get your cardio onto low-skill apparatus to focus on speed/output and not think about how sloppy your technique is getting. 

Do you have any tips/lifestyle advice for those looking to lose fat?

The key is to go at fat loss steadily. Fast 8-12 week shred programs offer you nothing. The goal is NOT to lose fat. Stay at that lowered fat / weight after a successful fat-loss phase. The reality is that you will need to stick with a lot of what you did to lose fat to sustain your new body composition. So you want to be making changes you can stick with. 

Don’t go too restrictive with food. You need enough energy to do your job / keep up with your family commitments, and exercise. It is better to start higher with energy intake and nudge it down gradually vs destroying your energy, libido, performance and relationship with food by going really low with caloric intake.

Sleep is key. You have already heard we use a third of the energy from fat during sleep. So, trying to ensure you can sleep well and for long enough is an important place to place your attention.

Ultimately, you want to be focused on your health. The more efficient your body is, the better it can use fuel and burn fat. Things like quitting smoking, cutting back on alcohol, saying no to the odd social activity that doesn’t align with you and doing anything you can to help unwind and destress can help.

As much as diet is the main driver, you want to become active. Take up a sport, get a standing desk, and book yoga retreats with friends versus a weekend in Ibiza. Start to shift your life in a direction of activity. 

Switch your mindset to being performance-driven with exercise. It’s NOT about the calories you burned (which won’t be even close to accurate). It’s about how strong you are, how fast you can run, how high you can jump. Your new mindset is more like an athlete, not a calorie tracker. 

And always remember that fat loss isn’t the goal. Sustaining the fat lost is. So whatever you do, you must stick with it for a lifetime. And with that in mind, remember there’s no rush to lose fat. The slower the rate of fat loss, the better chance you have of sustaining it. 

Don’t forget to follow me on Instagram, where I share exercise techniques and show you how to maximise your training. I hope you enjoyed this blog post, if you have any questions, I host a weekly  Q&A session on my Instagram channel. Otherwise, please feel free to email me at andy@andyvincentpt.com. 

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