The Science of Weight Loss: Understanding the Importance of an Energy Deficit

In the simplest of terms, the process of losing weight comes down to burning more daily calories than you consume over a period of time. This is known as an energy deficit, or more commonly, a calorie deficit.

Burning more calories than you consume is the ONLY true scientific way to lose weight.

Now, you and I both know that in the real world we live in, things are messy. And certain other things can control the weight loss process.

Things like hormones, amount of sleep, metabolism, insulin response, and a host of other factors affect how quickly you can lose weight, and how much your body wants to hold on to what it has.

But the bottom line doesn’t change. Permanent weight loss comes from eating fewer calories than your body needs to maintain its current weight.

This is where energy deficit comes into play. I know it doesn’t sound sexy and fun, and it’s rather to-the-point. But let’s not sugar-coat it just to make ourselves feel better.

Let’s instead learn how to make the concept work for us, in a manageable and relatively painless way. A way that we can embrace with joy, excitement, and flexibility.

The Science of Energy Deficit

The energy stored in food is measured in calories. We’re all aware of this, right? (In fact, a calorie as we know it is really a kilo-calorie or 1000 calories).

It’s the amount of heat required to raise the temperature of 1 kilogram of water one degree Celsius. But it’s easier for us to think in terms of a Calorie being just a calorie.

In any case, our bodies convert the food we eat into energy that fuels everything we do. Breathing, sleeping, walking, cooking, gardening, showering, and everything else you can think of.

calorie counting calculator with notebook

Even sitting still. Or watching TV.

What happens when we don’t use all that we eat in a day?

You guessed it, it’s stored mostly as fat, also known as “excess energy.”

What is Energy Compensation?

But there’s this thing called “energy compensation.” This is the process by which weight loss leads to lower energy expenditure and greater desire to eat!

What the heck? What this says is that, if you lose weight (because either you want to look better, and/or you have weight-related health issues), your body, mind, and hormones will conspire against you!

These concepts, by the way, are the real reasons that you’re constantly bombarded with “diets don’t work!” rhetoric all over the place.

Diets DO work, but we have hardwired physical and psychological challenges that need to be overcome in order to counter this evolutionary debacle.

Of course, it’s not really an evolutionary debacle. If we evolved with these processes, it means we needed them to survive at some point. We just generally don’t need them now.

But knowledge is half the battle. Just knowing this gives us an edge. Only now we need to figure out how to gently offset the natural physiological responses.

Outsmart them, kind of. But outsmart them in a sane, healthy, and most importantly, SUSTAINABLE way.

Three Ways To Create An Energy Deficit

There is no magical way to lose weight. Creating an energy deficit is really all we have. With that in mind, what are the ways to create such a deficit?

Reduce Portion Size of Meals & Snacks

This one is pretty much a no-brainer.

You can eat fewer servings of calorie dense foods, or smaller servings. Especially if these foods provide little to no nutritional value.

Examples here would be alcohol, sugary or fatty treats, fatty meats, deep-fried foods, nuts, most cheeses.

plate of food showing portion control

Some studies even show that ultra-processed foods eaten in abundance cause excess weight gain after returning to normal diets! That’s a bit scary.

Note that not all calorie dense foods are considered unhealthy. Nuts and avocados, for example, have high energy density, yet in controlled portions, they can be very healthful foods.

Decrease The Energy Density of Your Food

This is one of the best answers to a satisfying lower-calorie eating plan. Let’s face it, not many people want to go around with their stomachs growling all the time.

I know when I am feeling really hungry, it’s easier to overeat because I tend to eat too quickly. But filling up (reasonably) with each meal makes it easier to wait until the next meal time.

And you can do this by eating foods that have a lot of volume without a lot of calories.

Let’s see, what types of foods make up this category? If you guessed most fruits and vegetables, you would be correct! We just can’t seem to get away from those, can we.

You may be unlike me and can’t get enough veggies in your diet, but I have to figure out clever ways to add them.


Fruits are generally easier because they’re sweet. You don’t want to go hog wild on fruits, but even eating an extra serving here and there is better than a dish of ice cream!

Increase Your Activity

Okay, here’s where exercise comes in. I’ve stated before that exercise is non-optional if you’re over 50. This isn’t solely because of weight issues, but because we want to keep flexible, strong, and hopefully osteoporosis free well into our old age.

But don’t worry. Exercise doesn’t have to mean boring treadmill runs or walks, going to a gym if you don’t want to, or engaging in complicated workouts that require thousands of dollars in equipment.

Walking is an especially good way to use extra calories. All of us can walk, and if you walk at a decent pace, you’ll be surprised at how much it adds up over time.

I like using a pedometer to count my steps each day. I am working toward 10,000 per day and I’m getting closer!

The very best way I find to add more walking is to do it 10 or 15 minutes at a time. Another sneaky way is to use a step that’s 4″ or so high and walk up and down that while you’re watching TV or talking on the phone.

There are also numerous 10-minute workouts on YouTube. Who can’t find 10 minutes once or twice a day?

How To Win The Energy Deficit Game

You need to practice portion control, and think of food in terms of quality rather than quantity.

Some foods you can eat in abundance and still maintain an energy deficit. Focus on those that contain more nutrients.

Don’t drink your calories.

Drink water to quench your thirst instead of reaching for fruit juice or worse, sugar-laden soft drinks. Limit alcohol as well.

glass of white wine

I LOVE Chardonnay, and I like to drink it every night. I have trained myself to have one glass in the evening by simply starting later and sipping slowly.

Could I eliminate it entirely during the week? Yes, and that is the eventual plan.

Limit highly processed foods.

You know what these are: sugary beverages, high-sugar and fat desserts, many fast foods, deep-fried anything.

But no need to avoid these entirely, especially when you’re just starting on this journey.

That could ultimately backfire. Instead, start replacing them with healthier but still delicious and satisfying alternatives.

Cook more meals at home.

This is sometimes the hardest part of starting and maintaining healthier eating. And it could be for a variety of reasons.

You don’t know how to cook; you don’t think you have enough time; it’s too expensive (yes, some people seem to think this is so); you hate grocery shopping.

Yet, in reality, you don’t have time NOT to make most of your meals at home. When you cook and prepare at home, you know exactly what’s going in your body.

woman cooking healthy food at home

You can even get superior ingredients and at a much lower cost than if you eat out all the time.

Even if you mostly eat fast foods.

For example, my husband and I once a year or so have a hankering for a hamburger and a bag of McDonald’s fries.

To us, there is just no better-tasting fry than at Mickey D’s.

The total bill for this recently was $18.24 including tax (in Washington state). I can buy groceries for one person per week of around $25-$35, so you can see even this hamburger/french fries meal was kind of a money splurge.

Not to mention a calorie splurge!

How Can You Create & Use An Energy Deficit?

Now it’s your turn to go make a plan for ways you can implement this concept of energy deficit–if you have a goal of losing weight, of course! If you don’t need to, many of these concepts are still excellent for maintaining your weight in a healthy way.

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