The Science Behind Fat Loss

Author: Grow Team
Date: 21/03/2018
Category: Nutrition

Last week at Grow, we were lucky enough to welcome to the studio Richard Scrivener, master Personal Trainer and expert in the health and nutrition field. He treated us to a fascinating talk delving into the science behind achieving what is arguably the single most popular health and fitness goal: fat loss. Here, we sum up the key takeaways from the talk.


Weight loss

Keto. Paleo. Juice cleanses. Weight-watchers. Intermittent fasting. High fat. Low fat. High carb. Low carb. It seems as though every week, a new diet craze appears, promising to be THE best way to shred excess weight. It can be pretty overwhelming trying to separate fact from fad… But it doesn’t have to be. Let’s take a step back. Some of these diets appear to be founded on dramatically different principles, but, crucially, they actually all work in the same way: by creating a calorie deficit.


Yep, that’s right. It’s nothing new, and it may not sound as exciting as the latest fancy diet being promoted by your favourite Hollywood A-lister, but when you break them down, that’s all any of these diets boil down to.


Granted, there are a LOT of variables involved in weight and fat loss – as demonstrated by Shiftn’s mind-boggling diagram below, that maps the drivers of obesity. As you can see, there is a complex web of variables that interact to influence someone’s risk of becoming overweight. These range from socioeconomic factors like employment type and cost of exercise, to individual social and psychological factors such as stress and childhood experiences with food, to biological factors like resting metabolic rate.

However, as you can see on the diagram, they all ultimately loop back in some way in some way to the core driver of weight gain at the very centre of this map: energy balance. Which means that “burn more calories that you eat” is STILL the best advice if you want to lose weight. Because it’s the only thing that has been proven, consistently, to get results. If you want to gain weight, you need to provide your body with more energy than it needs to maintain its current weight. If you want to lose weight, you need to burn more energy than your body needs to maintain its current weight. It’s simple, it’s scientifically proven and it’s effective.


The importance of NEAT

Richard highlighted a puzzling trend, that at first glance appears to contradict the “calories in, calories out” idea. In the UK, the last few decades have seen people buying fewer calories and doing more exercise… So naturally, we’d expect our waistlines to be shrinking. But we all know that isn’t happening! In fact, we’re seeing the exact opposite, with rates of obesity soaring. How could this be? It all becomes clear when we consider NEAT – Non-Exercise Activity Thermogenesis. Bear with us – it’s not as complicated as it sounds.


Put simply, NEAT is all the activity you do outside of planned workouts. There has been a steep decline in the number of calories we burn via NEAT, because unfortunately we have become a lot more sedentary as a nation. We drive more instead of walking, spend more time sat at our desks, and are far more likely to indulge in a game of FIFA with the kids than actually go outside and have a kick-about with a real football.


It’s really important to do both structured exercise AND stay active throughout the rest of your day. The easiest way to drive up energy you burn via NEAT is simply by walking more, however if you chat to our trainers they will happily share lots of ideas with you. Take the dog for an extra walk, do some stretching in the ad breaks, get off the bus a stop earlier than you need to – small changes like this will make a surprising difference, helping you to burn extra calories and shift stubborn weight.


Fat loss

So, we’ve established that if you want to lose weight, then the key is to consume fewer calories than you expend, both through structured workouts and generally moving around as much as possible. But most people don’t just want to lose weight – they want to shred body fat, while maintaining muscle, to achieve that lean look that we all aspire to. To reach this goal, we need to do a little more than simply create a calorie deficit – we must also consider how much exercise we do, what kind of exercise we do and the amount of protein that we consume.


Exercise is a “partitioner” of calories, which, simply put, means that it directs them to different areas of the body and tells them what to do. If you eat in a calorie surplus and exercise, then it is likely that those extra calories will be used as fuel to build muscle. If you eat in a calorie surplus and don’t exercise, then you’ll gain fat. Conversely, if you eat in a calorie deficit, you’ll lose weight whether you exercise or not, but doing exercise will ensure that you maintain muscle while losing fat. Without doing exercise, there’s a risk that 30% of the weight you lose will actually be muscle, not fat.


When we say exercise here, we’re referring specifically to resistance training. This is any form of exercise where you lift or pull against resistance – this could be bodyweight (e.g. press ups), dumbbells, a barbell, resistance bands, kettlebells or cable machines. Cardio will help you to lose weight, by driving your body into an energy deficit, however it won’t provide your body with the stimulus required to maintain muscle, so you are likely to lose muscle as well as fat if you rely solely on this type of training.



So, what role does protein have to play? Often, the first thing that springs to mind when we talk about this nutrient is muscle-building. And while protein does indeed have a crucial role to play in building muscle, it is also key in maintaining muscle, driving the body to burn fat instead of muscle when exercising. For this reason, we arguably need more protein when trying to lose body fat than we do if we’re trying to build muscle.


The government advises, via its Eatwell Guide, that around 10% of our daily intake should come from protein. This is actually very low, with recent research suggesting that we need at least 1.6 grams of protein per kilo of bodyweight and up to 2.2 grams. Let’s consider an example: a 70kg male, eating 2,500 calories per day. According to the Eatwell guide, he should eat roughly 250 calories of protein per day, or 62.5 grams. That’s less than 0.9 grams of protein per kilogram of bodyweight. If we alter his diet to follow the 1.6 or 2.2 grams per kilogram suggestions, his protein intake will increase to 112 or 154 grams of protein per day, respectively.  This difference in protein intake could be key in helping him to ensure that he burns fat and maintains muscle.


Adding more protein into your diet has the added benefit of helping you to feel fuller for longer, so if you’re in a calorie deficit this is really helpful, because it will help you to stop you feeling hungry as you lower your calorie intake. For more information on macronutrients including protein, check out our blog here.


Summing up

The key message from Rich’s talk is that fat loss needn’t be complicated. The key is to eat less than your body needs to sustain its current weight, including plenty of protein and doing regular resistance training to encourage your body to maintain muscle and burn fat. Outside of the gym, make sure that you remain active. Find something that works for you – whether that’s going for a stroll on your lunch break or doing some squats in the ad breaks – the important thing is to just move your body more.


If you need any further advice on what we’ve covered here, don’t hesitate to talk to the team at Grow – our instructors would be more than happy to help!


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