This video explains the fundamentals of a weight loss transformation.
I’m going to add some additional information here to help explain some of the underlying science that supports the ideas in the video. I’ll link to a few studies that shed light on the dynamic nature of our metabolisms, plus add a little general background;-)
It All Starts With A Deficit
In the video I described how you can begin a weight loss transformation if you apply a 20% deficit to your maintenance calories. So why don’t we begin by defining what a calorie deficit is.
A caloric deficit is when we expend more energy than we absorb from food over a set period (typically a day). Creating a deficit forces the body to meet the energy shortfall from its energy stores (glycogen, muscle tissue and body fat). With glycogen in relatively limited supply the aim is to maximise the energy dragged from fat cells by maintaining as much muscle mass as possible.
The whole concept is a lot easier to explain visually:
In this graph the caloric deficit is the section in the middle. This is the amount of energy the body has to draw from its energy stores to maintain energy balance. On the left hand side is the energy absorbed from all the food and drink that is eaten in the day, and on the right hand side is the energy expended.
Energy expenditure is the sum of energy used by the body in the day. For almost everyone but athletes and physical labourers resting metabolism takes up over half of expenditure, digestion of food is around a tenth of total calories. Activity from general and subconscious movement like fidgeting can vary greatly between people, and exercise is typically a smaller fraction with the exception of athletic individuals.
Bottom line: In a deficit the body draws energy from its stores
Your Three States of Energy Balance
Throughout the video we were mostly looking at losing weight (the deficit), but you should really understand the other states of energy balance too.
The state of positive energy balance, where we eat more than we expend, is called a caloric surplus. This is how we gain weight and is a common occurrence in the holiday periods and often at weekends too. A small caloric surplus is a good state to be in when you are trying to gain some muscle and it increases your time spent in an anabolic state.
When energy consumption matches expenditure, and things are roughly balanced out, this is what we call maintenance. Although energy stores are never truly static, if you are maintaining a stable weight then your average daily calorie consumption will be close to maintenance. Working out what this is before you start a diet is a very good idea!!!
Here’s what the three states of energy balance look like:
I’ve added a bunch of arrows and some clues about hormones to highlight that our energy balance is a dynamic system. Our bodies have a hormonal defence system that works to maintain homeostasis (stable weight).
When you start to gain weight it ramps up energy expenditure and dampens hunger. When you start to lose weight it reduces energy expenditure and increases hunger. This internal thermostat is one of the main reasons its very hard to keep weight off in the long run.
Bottom line: Energy balance can be in surplus, deficit or maintenance
How You Adapt to Overfeeding
In the video I mostly focused on how our energy needs adapt during weight loss, but this cuts both ways. The following graph comes from a really famous study that coined the phrase ‘nonexercise activity thermogenesis’ (NEAT). In the study James Levine and colleague took 16 healthy individuals and overfed them each by 1,000 calories a day for 8 weeks.
Here is a graphical summary of what happened to their energy balance.
The average weight gain across the 8 participants was about 10 lbs (4.7kg), less than half of what a static energy balance calculation might predict. What they found was that by the end of the eight weeks average energy expenditure had increased by 554 calories a day, reducing the surplus by over 50%. People’s bodies used more energy in response to overfeeding.
Perhaps even more fascinating was how the weight gain and expenditure varied amongst the group. The weight gain ranged from 3lbs (1.4 kg) up to 15 lbs (7.2 kgs). The thing that caused most of the variation was how activity changed (their NEAT response). This went all the way from a 98 calorie drop to a massive 692 calorie increase. The conclusion was that some people have a strong activity response to overeating, helping them stay naturally slim, while others are weak responders predisposing them to a higher obesity risk.
It’s also important to remember overeating can have a time and place. The benefit of eating more to upregulate your metabolism is reflected in nutrition protocols like re-feeds, diet breaks, cyclical diets and fasting protocols (the non fasting days).
Bottom line: We adapt to overfeeding by increasing expenditure
How You Adapt to Dieting
Just as our body adapts to overeating, it will also adapt to going on a diet. I stressed this in the video.
Tragically, for those of us looking to lose weight there is some evidence that our bodies are much better at defending us from fat loss than they are at protecting us from fat gain. This makes sense from an evolutionary perspective as getting very lean leads to reproductive problems, whereas having extra fat might have been quite useful during periods of food scarcity.
To provide another visual example I grabbed some data from a great free living study that looked at how people adapt to caloric restriction. I’ve used data from 12 people that were placed on a 25% caloric deficit for three months. Here’s what their average adaptation looked like:
Over the three months on a 25% calorie restriction the 12 healthy individuals in the group lost an average of 13 lbs (6kg). After three months on the diet the original 712 calorie deficit had been reduced to just 258 calories.
Average energy expenditure fell by 454 calories, mostly drops in activity and to a lesser degree resting metabolism. The adaptation was 371 calories greater than what was expected from the change in muscle and fat mass alone. This additional loss in expenditure is what people in the field call ‘adaptive thermogenesis‘.
Basically the whole process of losing weight results in the body getting more efficient in maintaining cells, organs and tissues, as well as reducing our subconscious activity in order to conserve energy. This makes regaining weight particularly easy to do after significant weight loss, and may explain part of the reason a majority of people who have lost a lot of weight and kept it off do a lot of exercise each day.
While it’s easy to take a rather defeatist approach to this information it can also be super useful. Not only does knowing some level of adaptation is inevitable make you more patient, but it serves as a reminder that maintaining a healthy metabolism should be a priority for everyone losing weight.
Bottom line: We adapt to dieting by decreasing expenditure
Planning Your Own Transformation
Transforming your body doesn’t happen in days or weeks. It happens over months or even years. The most important element of any transformation is to focus on the deficit.
Why? Because the deficit is the energy shortfall you need to lose fat. Here’s a different take on what ‘focus on the deficit’ means visually for someone who is prepared to use exercise together with diet to achieve their goals:
The image above is a stylized version of what a six month fat loss program could look like for a man going from 180 lbs (82 kg) down to around 160 lbs (73 kg). Our area of focus is the caloric deficit, the section coloured with grey stripes above the energy consumption but below energy expenditure.
The dynamic nature of energy balance means that energy expenditure (the orange line) is affected by energy consumption (the black line). So the adjustments we make to diet and exercise will change depending on where we are at in the diet cycle.
Unlike the simple example in the video, in this graph the trainee also uses weights and cardio to expend more energy. The major advantage of exercise during weight loss, and strength training in particular, isn’t so much that you burn extra calories but that you partition more calories into your muscles. This will result in a far healthier and better looking body when the weight comes off.
Bottom line: Focus on the deficit for better results
How Do I Get Started?
In the video I noted that a 20% deficit is a good place to start a diet. For my male example this resulted in a starting target of 2,400 calories a day, and for my female it was 1,900 calories.
Please don’t assume you are this person!!
Starting 20% below your maintenance is a great idea, but we have no idea what your maintenance really is. Here’s what the true energy needs of men and women look like:
If you are willing to track your food and weight you can make a decent estimate. Then the process looks like this:
- Estimate your maintenance
- Apply a 20% deficit to get your target
- Try to eat this consistently for 5 weeks
- Assess your weekly loss in weeks 2-5
- Adjust your calories to lose 0.5-1% per week
If you’re not prepared to track your food, the best advice is probably to make an educated guess and then monitor your results. If you use a calculator, remember it’s just a guess. If you are consistently losing 0.5-1% of body weight a week you can be pretty sure you’re nailing the deficit. The proof is in your pudding 😉
Bottom line: Be consistent and track your results
For a further discussion about maintenance calories grab 5 Simple Strategies to Start Losing Weight, then you’ll be added to the email series with videos covering this stuff.