The Science of Calorie Restriction: Going beyond Fat-loss

5 unhelpful myths debunked so you can make the most out of calorie restriction.

Calorie restriction is a nutritional approach that cuts daily caloric intake to less than typical, usually by 10–25%, while consuming adequate nutrients to avoid malnutrition.

Calories measure the amount of energy people derive from foods and drinks to live and function. Each gram of carbohydrate or protein packs four calories, while a gram of fat holds nine.

Calorie restriction is not only a wildly popular method for weight loss but also an effective strategy to live healthier and longer. To get the most out of it, steer clear of the following widespread misconceptions.

Myth #1: Calorie restriction is only for those who seek fat-loss

On the contrary, calorie restriction offers a slew of benefits beyond fat-loss:

1. Slows cardiac aging and impedes the build-up of fats and cholesterol plaque in artery walls, boosting heart health and mitigating the risk of cardiovascular disease.
2. Protects against chronic medical conditions, such as obesity, type 2 diabetes, inflammation, hypertension, and metabolic risk factors associated with cancer.
3. Although the mystery of how remains unsolved, calorie restriction’s ability to extend lifespan has been known for several decades.

In other words, even a healthy human with washboard abs and low body-fat percentage can benefit from moderate calorie restriction.

Myth #2: ‘A calorie is a calorie is a calorie’

Yes, every calorie has the same amount of energy — 4,184 joules. So a calorie from a donut must be the same as a calorie from a banana right?

No. The effects of different caloric sources on appetite, hormones, energy use, and blood sugar levels vary sharply. Here are the mechanics:

1. Nutrients have unalike thermic effects

Thermogenesis, or the thermic effect of food, is the energy spent to digest, absorb, and dispose of ingested nutrients. So the energy we derive from foods is decreased by their thermic effects.

The thermic effects of macronutrients are dissimilar, representing energy losses of 25–30% in proteins, 6–8% in carbohydrates, and 2–3% in lipids. In other words, 100 calories would translate into 75 effective calories if the energy source is protein, 94 if it’s carbohydrates, and 98 if it’s fatty.

Energy-wise, proteins are absorbed inefficiently by the body, offering a metabolic advantage.

2. All carbohydrates are not equal

The Glycemic Index (GI) rates carbohydrates based on how swiftly they raise blood sugar levels.

High-glycemic foods are quickly digested, causing rapid spikes in blood sugar levels. They induce hunger cravings and and may promote body fat gain.

In one study, participants ate 81% more calories after a high-GI meal than a low GI-meal. The swift absorption of glucose induced hormonal and metabolic changes that encouraged excessive post-meal food intake.

Conversely, several studies demonstrate that low-glycemic foods promote fullness and decrease later food consumption.

Potatoes and refined grain products, such as white bread or white rice, tend to have a high GI, even exceeding that of table sugar. In contrast, most vegetables, fruits, and legumes have a low GI. Here’s Harvard Medical School’s handy list of 60 common foods and their GIs.

Bottom line: a food’s GI impacts hormones, appetite, and body-fat gain.

3. Processing makes energy in food more accessible

Food processing, such as cooking, increases the energy gained per calorie by making food more digestible. It lowers the effort, and the energy cost, of the body to metabolize and assimilate nutrients.

Raw foods require more metabolic effort to break down, and are often not digested and absorbed completely, limiting the energy gained from a calorie.

As a result of this disparity, this study concluded that calorie-counters who ate similar diets (and exercised the same amount) but cooked their foods to different extents would experience varying amounts of weight gain (or loss).

We extract more energy from the same foods if we eat them cooked rather than raw. Our calorie-counting system overestimates the energy we gain from raw, unprocessed foods by ignoring digestion costs.

While these phenomenons make calorie-counting more complicated, it’s imperative to understand why a calorie from a donut is not the same as a calorie from a fruit.

Calorie-counting is not an exact science. Nevertheless, many studies show that it works; people who count calories are likelier to lose weight than those who don’t.

Myth #3: You have to withstand hunger in a calorie deficit

Hunger is not an inevitable part of calorie restriction — it’s shaped by food choices and eating habits.

Some foods are less filling, more calorie-dense, and easier to gobble up than others. To illustrate: five regular dates have the same amount of calories as three cups of chopped broccoli and twenty cups of arugula.

The satiety index of foods

Measures the ability of foods to curb hunger, increase fullness, and subdue caloric intake over the next few hours.

Eating foods low on the satiety index will leave you hungry and craving more food, whereas consuming those high on the satiety index will keep you sated for longer.

Foods containing water, fiber, and protein score high on the satiety index, while fatty, sugary, and ultra-processed convenience foods score low.

A study found that increasing protein intake to 30% of daily calories drove participants to consume 441 fewer calories every day, and lose 4.9 kilograms, or 11 pounds, in 12 weeks.

In another study, participants on a diet of ultra-processed foods (white bread, processed meats, fruit juice concentrates) consumed 500 more calories a day than those on a diet of minimally processed foods (fruits and vegetables, grilled fish).

To fend off hunger, choose satiating foods, which tend to be whole, raw, rich in protein, fiber, or volume.

Myth #4: Skipping meals is the only way to restrict calories

While systematically skipping meals, or fasting, is an effective means of calorie restriction, it’s not the only way. Other ways include: switching to lower-calorie foods, controlling portion sizes, or following hara hachi bu.

Héctor García and Francesc Miralles explore the ancient Japanese concept of hara hachi bu in “Ikigai: The Japanese Secret to a Long and Happy Life.” It loosely translates into “fill your belly to 80 percent.” The subjects of this book — one of the world’s longest-living people, the Okinawans — restrict calories by ceasing to eat before they feel full.

The idea is to stop eating when you’re almost full — don’t reach for that last snack or dessert to polish off your meal. Be “a little bit hungry when you finish.”

While this might seem implausible at first, eating slowly and paying attention to signals from your body can help you determine when you reach this point. It’ll become effortless over time.

Myth #5: Self-control is the key to calorie restriction

Willpower is not as significant in maintaining a calorie deficit as most people think. Habits and environment matter more.

Psychologists have found that people who appear to be adept at self-control tend to structure their lives in a way that rules out the need for self-control decisions. They simply spend less time in tempting situations.

If your office pantry is always stocked with chips and donuts, you might grab one now and then.

Reduce the need for self-restraint by making your environment conducive to the choices you want yourself to make.

Besides, achieving a calorie deficit is arguably not as restrictive as other diets. You can eat anything you want.

Such as a chocolate croissant. It’ll use up a portion of your daily caloric intake without appeasing your hunger for long, but it’ll be a party for your tastebuds. Exercise moderation though — after all, a calorie is not a calorie, and you don’t want to be starving later.

Final word

Many benefits of calorie restriction, such as disease prevention and longevity, emerge over time, so choose a calorie restriction goal that’s sustainable for you. If you choose to restrict calories, be sure to:

• Stay healthy by picking nourishing, nutrient-rich foods and avoiding high-calorie, nutritionally-paltry foods. More superfoods, less sugary fares.
• Consider the satiating, metabolic, and hormonal effects of foods, instead of opting for items solely based on their calorie-count. Include protein and fiber-rich ingredients in your diet, such as vegetables and legumes, and forgo high-glycemic foods, like white pasta.
• Recognize that skipping meals and exercising boatloads of self-control are not necessary to maintain a calorie deficit. Your environment, habits, and food choices play a larger role.

Build your menu around minimally processed, nutrient-rich, satiating ingredients, and prime your environment to make healthy choices easier.

And you’re all set!

If you enjoyed this story, click here to receive an alert when I publish something new!