Is a calorie just a calorie?

Is a calorie just a calorie?

In short, no. In the end it comes down to quality not quantity. 

The “calorie” myth is one of the most pervasive when it comes to nutrition. For those concerned with weight loss or weight management it’s important to focus on the right kinds of food. While a calorie is simply a unit of energy, how and where that energy is derived has a significant impact on our bodies. 

What is a calorie?

Simply put, a calorie is a unit of energy. It indicates how much fuel or heat is provided by a certain food. Even more specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (we’ll keep measurements in metric terms, as it’s a far simpler system). When we refer to calories in terms of nutrition, the kilocalorie is used, where 1,000 calories (cal) is equal to 1 kilocalorie (kcal); to further clarify, the nutritional calorie is capitalized.

Are all calories equal?

From an energy perspective, a calorie is just a calorie. One hundred kilocalories will provide the same amount of energy whether they are derived from potatoes, meat, or olive oil. However, from a nutritional standpoint, the source of those calories is important. The body metabolizes energy from macronutrients differently, leading to different outcomes and body composition when we consume carbohydrates, proteins, and fats.

Why is nutrition important (in other words, why should we care about calories)?

If we want to understand the basics of all calories, we should first clarify that no matter how one eats, the majority (about 80 to 90 pct) of health and nutrition goals are dependent on what is eaten. The truth is that one can exercise five to six days a week, which will improve certain cardiovascular functions, but will not help with body transformation.

Simply speaking, eating more will cause weight gain, while eating less will cause weight loss –  to be clear, this doesn’t take into account body composition, which can also change. For example, limiting calories can also cause muscle loss, changes in physical performance, or energy levels.

Overall health is largely dependent on what we put into our bodies. How so? Well, think of how long it takes you to eat a meal. According to WebMD, it takes on average 20 minutes to eat a meal. If you think of your calorie intake in thirds (we’re assuming three meals per day), where the USDA estimated calorie requirement for sedentary men aged 21 – 40 is 2,400 calories (for women, it’s a little more varied with 1,800 to 2,000 set as the range), in 20 minutes 800 calories are consumed. So, how long does it take to burn those 800 calories? A chart from the Mayo Clinic can give a little more insight below:

 

Weight of person and calories burned

Activity (1-hour duration)

160 lb (73 kg)

200 lb (91 kg)

240 lb (109 kg)

Aerobics, high impact

533

664

796

Aerobics, low impact

365

455

545

Aerobics, water

402

501

600

Backpacking

511

637

763

Basketball game

584

728

872

Bicycling, < 10 mph, leisure

292

364

436

Bowling

219

273

327

Canoeing

256

319

382

Dancing, ballroom

219

273

327

Elliptical trainer, moderate effort

365

455

545

Football, touch or flag

584

728

872

Golfing, carrying clubs

314

391

469

Hiking

438

546

654

Ice skating

511

637

763

Racquetball

511

637

763

Resistance (weight) training

365

455

545

Rollerblading

548

683

818

Rope jumping

861

1,074

1,286

Rowing, stationary

438

546

654

Running, 5 mph

606

755

905

Running, 8 mph

861

1,074

1,286

Skiing, cross-country

496

619

741

Skiing, downhill

314

391

469

Skiing, water

438

546

654

Softball or baseball

365

455

545

Stair treadmill

657

819

981

Swimming laps, light or moderate

423

528

632

Swimming laps, vigorous

715

892

1,068

Tae kwon do

752

937

1,123

Tai chi

219

273

327

Tennis, singles

584

728

872

Volleyball

292

364

436

Walking, 2 mph

204

255

305

Walking, 3.5 mph

314

391

469

Yoga, hatha

183

228

273

Yoga, power

292

364

436

Source: http://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/exercise/art-20050999

From a baseline of 160 lb, only running (at 8 mph) and rope jumping will get those calories burned. Given the calories in vs calories out imbalance, it’s far easier to limit calories consumed than it is to exercise them off. One thing to keep in mind is that the 800 calories calculated per meal represent the number of calories recommended, not what’s actually consumed by the average American.

Are all calories, created equal?

To start things off, here’s a staggering statistic. In the USA, an average of 3,770 kcal are consumed per capita, the highest of all countries surveyed. On average American males weigh 195 lb and measure, 5’10” while females measure 5’4” and weigh 165 lb. That’s a good amount of excess weight we’re carrying and could really afford to lose. In order to lose that weight, less calories would need to be consumed or burned off – to the tune of 500 calories per day to lose one pound of mass per week.

Keep in mind this is weight (mass) loss and not fat loss – an outright targeting of calories will likely result in a decrease in muscle mass as well. While this is beneficial for individuals who need to simply get down to a more acceptable BMI, the actual process of losing fat is far more involved than a simple reduction of calories – this answers the question of whether a calorie is just a calorie.

Macronutrients and the burning question – is there really an ideal diet?

What calories don’t take into account by themselves are macronutrients - the substances that provide energy. Macronutrients are grouped into three main categories: carbohydrates, proteins, and fats (while alcohol also provides energy (approximately 7 kcal/g), it isn’t required for normal body functions and is therefore left out). Both carbohydrates and proteins provide 4 kcal/g, while fat provides 9 kcal/g.

This begs the question, is there an ideal diet? While most of our blends follow the Zone diet principles of a 40 / 30 / 30 macro ratio, where 40 percent of calories come from carbohydrates, and 30 percent from proteins and fats, we don’t think there’s an ideal diet. Simply speaking, we’re all created differently, and have different goals. However, we’ve chosen the Zone diet principles (for most of our meal replacement blends) as it’s closer to the pre-1977 USDA guidelines than what we have today, which have closely followed the growing trend in increasing waistlines. Even so, we acknowledge that correlation does not imply causation, and find that the culprit is actually two-fold. If we look at the graphs below, we can see that starting around the late 1970s and early 1980s two important changes happened. The graph on the left-hand side shows how we’ve increased our consumption of calories in general over time, while the one on the right-hand side shows how we’ve increased our consumption of carbohydrates at the expense of fat.

Macronutrients per capita per day in the USA

Food energy per capita per day in the USA

 

 

Source: USDA – Nutrient Content of the US Food Supply, 1909 – 2000

While we can’t single out whether it’s the increase in calories consumed by themselves, or whether the increase is a result of a reliance on simple carbohydrates, it has been illustrated that junk food can be highly addictive, which can therefore lead to greater consumption.

How macronutrients are absorbed

Each macronutrient serves a different function. Carbohydrates are recognized as the body’s main source of fuel that are essential for the body’s nervous system, the kidneys, the brain, and muscles. Proteins are used by the body for growth, tissue repair, immune function, essential hormone and enzyme creation, and preserving lean muscle mass. Fat, in turn, is used for normal growth and development, energy, micronutrient absorption, and maintenance and protection of cells and organs.

Without getting too technical on the process of how carbohydrates, proteins, and fats are absorbed, we’ll provide a simple chart on how each is different.

Is a calorie just a calorie? Sources of ATP (i.e. energy)

Source: http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@6.17:163/Anatomy_&_Physiology

Carbohydrates are readily absorbed by the body and are essentially the macronutrient that’s used first. They begin their breakdown in the mouth, and are converted to glucose that can be absorbed by the small intestine. Whenever an excess amount of carbohydrates are consumed, the liver stores the remainder for use between meals to help regulate blood sugar levels. Once the liver is satisfied with the amount of carbs it has, the rest is stored as fat for later use.

Proteins are broken down into amino acids that are used to build new proteins (amino acids). Amino acids are used to maintain or build muscle – this can only happen if the muscles have been subjected to strain and stress –, but can also be used as energy when there’s a shortage of carbohydrates or fats. Excess amino acids are simply excreted in urine.

Fats are broken down into fatty acids that are readily used by cells, with the remainder bundled as triglycerides and stored in fat cells for later use.

In short, we can see that the body absorbs the nutrients it needs from the source at hand; whatever energy isn’t needed or stored within the liver get stored as fat for later use. Carbohydrates are the macronutrients most efficiently absorbed by the body and converted to energy. While this is good in terms of rapid absorption, our currently high calorie, carb-laden diets create an environment that is prime for excess fat storage.

Is a calorie just a calorie?

So, based on our original question – is a calorie just a calorie – we can see that not all calories are created equal and can end up affecting the body in different ways. What is clear is that whether calories are derived from carbohydrates, proteins, or fats, an excess consumption of calories will result in the storage of body fat. If seeking to reduce body fat, the easiest way is to do so is to consume less calories; exercise will help accelerate the process, but will likely not be able to achieve this alone.


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