What Actually Matters For Fat Loss Part 2
What Actually Matters For Fat Loss Part 2
The Energy Out Side of Things
In the first part of this series, we covered what matters for the Energy In side of the energy balance equation. In this one, I'll give a breakdown of what the calories we burn are used for and how to influence the Energy Out side of the equation for better fat loss outcomes.
Energy expenditure can be broken down into 4 parts:
Resting metabolic rate (RMR)
Diet-induced thermogenesis (DIT)
Exercise activity thermogenesis (EAT)
Non-exercise activity thermogenesis (NEAT)
I'll go over each one and explain how to increase them.
Resting Metabolic Rate
~50-70% of energy expenditure, how the average person burns most of their calories
Resting metabolism is the energy required to operate at rest. If you're lying down on your bed, the calories you burn make up your resting metabolic rate. You need energy for the cellular processes in your body, organ function, breathing, etc. For almost everyone, this is the biggest piece of the energy expenditure pie.
This makes sense when you think about it. We spend almost all of our day in this state, so although it doesn’t require much energy to idle for a few minutes or an hour, it adds up over 24 hours.
When most people use the term metabolism, they are referring to RMR, but you’ll see that how we use energy is more complicated than that. And because RMR doesn’t change that much, people would do well to not blame it for their fat loss woes.
How Do You Increase Resting Metabolic Rate?
Resting metabolism has the least variability of all of the factors because the processes responsible for it are mostly the same for everyone. This is why around 80% of the variance in RMR is due to body size.
Age is even a smaller factor in RMR than most people believed, as we saw in this recently published Science article.
Fat-free mass–adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults.
Almost all of the variability in energy expenditure comes from other factors, and I will go over why.
Diet-Induced Thermogenesis (DIT), aka Thermic Effect of Feeding (TEF)
~5-15% of energy expenditure
When we eat, we have to do stuff with the food. Break it down, transport it through the digestive system, absorb the nutrients from it, etc. That costs energy.
Diet-induced thermogenesis (DIT), which is sometimes called the thermic effect of feeding (TEF), is the amount of energy it costs to digest, absorb, metabolize, and store the food you eat. The size and energy content of the meal play the biggest role in DIT. So the larger the meal, the more work your body has to do to make use of it.
How To Improve Energy Expended Through DIT
Eat Unprocessed or Minimally Processed Foods
This shouldn’t be a surprise. It costs energy to process food, but if the food is already processed, we will need less energy to extract nutrients from it.
Minimally processed whole foods require more processing and thus we burn more calories to extract what we need from them. Simply switching to less processed foods can have a significant effect on energy expenditure.
Increasing DIT happens naturally the bigger you are since you need more food. Shocker. You can certainly influence it by eating more natural whole foods and by increasing your protein intake, to a degree, but I wouldn’t count on it being the primary driver for fat loss either.
That responsibility mostly lies with the last two components
Exercise Activity Thermogenesis (EAT)
~5-10% energy expenditure on average, but variable depending on activity levels, with more active people being above this range
Exercise Activity Thermogenesis (EAT) is the increase in metabolism from planned exercise. Planned runs, strength training, and adult group fitness class workouts all fall in this category.
Although energy expenditure from exercise is relatively small compared to resting metabolism for the average person, very active people will consume significantly more energy during exercise. It's a hard pill to swallow, but you burn relatively few calories through planned exercise. Our bodies are efficient at using energy because we are adapted to a low-energy environment. If we burned up lots of energy when we moved around, we wouldn't have survived when food wasn't so plentiful.
Most equations aimed at finding your maintenance calories will already account for activity level, so it's best not to think of the calories you burn during exercise as an allowance to eat more calories. If you're generally active, the equations you use to find your calorie target will account for extra energy burned already.
Here’s an excerpt from an article on EAT by Chung and colleagues that sums up the relative impotence of exercise as a primary player in energy expenditure for the average person:
Commonly EAT accounts for a maximum of 15-30% of TEE in those who regularly participate in the recommended physical training, and it explains 1-2% of the variance in TEE. However, for the majority of people in modern society, EAT is believed to be negligible. Also, adherence to the recommended exercise intensity and duration remains low in obese patients, and consequently, EAT is nearer to zero.
Increasing Exercise Can Help, But It’s Not A Panacea For Fat Loss
When most folks want to lose weight, they exercise like mad. They sign up for more classes, hit the gym more often, and go for more runs thinking that they can brute force a healthy body weight by throwing more expenditure at the problem.
Increasing structured physical activity, all else equal, will help tip the scales in your favor for fat loss. But you don’t burn all that many calories in a single bout of exercise, so you must be careful when “compensating” for poor dietary habits with exercise.
Make no mistake, regular exercise is a great thing. It can improve mood, sleep, increase bone density, ward off certain types of cancers, improve blood pressure, improve brain health, and a number of other benefits.
But it’s best not to think of its utility as the primary driver of fat loss, but rather as a single piece of a healthy lifestyle and weight management puzzle.
Non-Exercise Activity Thermogenesis (NEAT)
~15-30% Energy Expenditure, the most variable component of energy expenditure
NEAT is any activity that isn't planned exercise. Yard work, gardening, standing while working, and fidgeting are all examples of NEAT. NEAT is the most variable component of energy expenditure and can vary as much as 2000 calories between two individuals of similar sizes.
It's one of our body's natural defenses against losing weight during a caloric deficit and gaining weight during a caloric surplus, but the variability from person to person is massive, and changes are often subconscious. I, for example, notice that I get very antsy and hot after a large influx of calories, which often results in spontaneous movement, fidgeting, and general restlessness. The reverse is true when dieting for weight loss; my desire for movement decreases, and I tend to get colder easier.
A drop in NEAT is a huge culprit responsible for both sustaining the weight you’ve already lost and achieving further weight loss.
How do you mitigate the negative effects of NEAT?
NEAT adjustments are mostly subconscious, which means making a conscious effort to counteract its effects can be difficult. Rather than obsessing over miscellaneous movement throughout the day, it’s probably easier to focus on overall activity and using dietary strategies to make the whole process of dieting more tolerable and sustainable.
Get more steps
Step count targets are an easy way to ensure a certain level of activity. The step target will be unique to the individual; some folks can hit 10k steps with no problem, but others may want to start more conservatively, like 5-7.5k or even lower. You should always start with a daily step count you can realistically achieve.
Almost everyone has a fitness tracker or smartwatch these days, but if you don’t and want to track your daily steps, you can check out inexpensive clip-on pedometers.
Lose Weight Slower
Two conditions create the biggest pushback from your body when dieting: when you get very lean and/or when you try to diet on very low calories. Most folks don’t see much of the first one unless they’re physique competitors or have eating disorders, but the second one is extremely common. People want to lose weight fast so they try to diet on a thousand calories a day, not realizing they are working against their own ends.
Unless there is a medical need to lose weight fast, I always recommend a slower rate of weight loss. It’s not inherently better as far as the outcome (weight lost is weight lost), but it will likely lead to better adherence, you hating your life less, and is better for muscle-building if you’re also engaging in resistance training.
Focusing on a slower rate of weight loss and the accompanying patience it requires also forces you to change your mindset about the process as a whole. Rather than treating weight loss as a sprint, it’s better to focus on improving your strategy a day at a time and letting the chips fall where they may.
Take Diet Breaks?
Diet breaks are somewhat controversial and the nutrition and fitness professional world is split on whether they’re effective. Although there doesn’t seem to be great evidence that diet breaks result in better weight loss outcomes from a physiological standpoint, many coaches and professionals believe diet breaks can improve adherence, thereby improving outcomes indirectly.
But relatively new research indicates that they aren’t much better than continuous dieting for fat loss. So as with most strategies, if you struggle to diet for prolonged periods, you can try it and see how it works for you.
Protein Intake
I will talk more about protein’s role in mitigating the negative effects of dieting in the next section but know that adequate protein intake is crucial for holding onto lean tissue when dieting. As I mentioned in part 1, protein also plays a vital role in feelings of fullness, which can also help prevent overeating.
The Difference Between Weight Loss and Fat Loss
When we focus only on weight loss, we can also lose muscle, which isn’t what we want. What if I told you there was a way you could ensure the weight you lose is almost entirely fat?
Resistance Training
When you consistently eat less than your body needs to operate, you have to pull the energy from somewhere in your body. Most will be from fat storage, but some will also be from your lean mass (or muscle). Unless…you send a signal to your body that you need to hold onto that muscle, and that’s exactly what regular resistance training does.
Regular lifting signals to your body that you’ll need that muscle in the future, so your body will resort strictly to pulling energy from fat. Pretty cool, right?
This is one reason why lifting is so great. Not only will you be losing weight, but almost all of the weight you lose will be fat. As a beginner, you’ll likely build muscle in a deficit because the stimulus for muscle growth is so strong.
Protein Intake
Resistance training sends the signal, but protein intake gives you the raw materials and thus plays a role in maintaining lean mass when dieting.
Unless you’re extremely lean or dieting at very low calories—which I already mentioned isn’t a great idea—you likely still don’t need more protein than the upper limit of protein recommendations for the general population. Anywhere between 0.7-0.8g/lb bodyweight is likely fine for anyone that isn’t an advanced lifter or very lean, but the ramifications for not hitting this target are greater when dieting as the threat of muscle loss is greater.
Fat Loss Without Weight Change
Building muscle and losing fat at the same time is called body recomposition, and it’s much more common in new lifters and folks that are carrying more body fat. Because muscle growth and fat loss are independent processes and can happen at the same time, muscle growth can “mask” fat loss by adding weight to offset the fat you’ve lost. This is a good thing and one of the primary reasons I tell my clients not to worry too much about the scale.
So if you start a resistance training program and notice you’re not losing as much weight as you’d like, recomposition could be happening. If you really want to know, getting a DEXA at regular intervals can give you an idea of how your tissues are changing.
Summary
Fat loss is far from easy; if it were, we wouldn’t have an obesity epidemic that only seems to be getting worse. The concept is relatively simple: you need to burn more calories than you consume by either decreasing intake, increasing expenditure, or both, and you need to do it in a way that’s sustainable despite changes in metabolic needs as you lose weight.
An ideal fat loss strategy works on three fronts:
Decreases energy intake
Increases energy use
Improves nutrient partitioning (helps you hold onto muscle) with resistance training
Implementation of these items is challenging. It can be hard to know how many calories you’re consuming and burning, and we seem to be surrounded by options that set us up to fail on both fronts. And to top it all off, exercise is unpleasant and the rewards of doing it are often too far in the future to be motivating in the moment.
The third and final part of this series will focus on the more qualitative, practical, and philosophical aspects of implementing nutrition and physical activity changes.
Thank you for reading, and I will see you for part 3.