A calorie is a unit of measure. Calories tell us how much energy or heat is stored in the foods we eat. An article in the Journal of Nutrition states that the calorie was first introduced as a unit of heat in lectures about engines in 1819 and it wasn’t until 1894 that the calorie was used in discussions of human energy needs. Today, we most commonly think of calories in terms of cutting them– making sure that we aren’t consuming foods with too many calories throughout the day. But there’s more to learn, so let’s dive in and get a better understanding of how calories work.
A Calorie is Not Just Any Ol’ Calorie
There are significant differences among sources of calories, and they all react and interact differently in our bodies, depending on their origin. When it comes to weight loss, there is a huge difference in a calorie from carbohydrate, protein, or fat.
A study conducted by JAMA found that the participants who followed a high-protein, high-fat, and low-carb diet lost more weight than those on several other diets. It further concluded that a low-carbohydrate, high-protein, high-fat diet might be a “feasible alternative recommendation for weight loss.”
What We Know About A Calorie-Restricted Diet
The government funded a rigorous and long-term study on the effects of calorie restriction, called CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy). In this study, participants consumed 12% fewer calories over two years compared to the control group.
Participants in the experimental group experienced a 10% loss in body weight, reduced blood pressure and cholesterol, and a decrease in inflammatory factors and thyroid hormones. Favorable effects also noted in the restricted calorie group include improved quality of life measures such as mood, sexual function, and sleep.
Calorie Restriction Is Suitable Even for Healthy Individuals
Research shows that even lean, or slightly overweight, young and middle-aged individuals showed health benefits from calorie-restricted diets. In this particular study, all subjects who participated in the restricted calorie diet showed improvements in all health metrics measured, including systolic and diastolic blood pressure, LDL-cholesterol, and total cholesterol to HDL-cholesterol ratio.
Further, after two years, calorie-restricted subjects showed remarkable improvements in other health risk factors such as C-reactive protein, insulin sensitivity index, and metabolic syndrome score relative to the control group. The health benefits from calorie restriction were beyond any health benefits that may have resulted merely as a loss of weight in the experiment group.
More on Eating Less
Eat less and age slower? That’s what one study suggests. What they found was that reducing calories made participants’ metabolisms slow down, because cells became more efficient and used less oxygen. The byproducts of oxygen use in cells are free-radicals. Free-radicals are known to be responsible for much of the damage our bodies suffer as a result of aging.
It’s not all good news though. Valter Longo, who studies longevity at the University of Southern California, says Restricting calories and the subsequent slowing of your metabolism could cause problems. It could become progressively harder to keep weight off and end up resulting in a net weight gain.
How Food Density Plays A Role
Researchers at the CDC (Center for Disease Control) state that energy density is the number of calories in a gram of a specific food. The trick to eating to satisfaction and still reducing calories is to eat lots of low-energy dense foods.
In general, foods with a lower-energy density (i.e., fruits, vegetables, and broth-based soups) tend to be foods with either a high water content, lots of fiber, or little fat. Most high-fat foods have a high energy density, but one way of lowering the energy density of mixed dishes such as stew, chili, and casseroles is to add lots of vegetables.
How to Start a Calorie Restricted Diet
A major concern in calorie-restricted diets is adequate consumption of vitamins, minerals, and other essential elements. A good multi-vitamin helps, as anyone trying to reduce their calorie consumption can potentially experience a deficiency in vitamins.
Many resources will tell you to become very well informed before beginning to reduce calorie intake and the information almost makes it sound as if your life is in serious danger from reducing calories. While this is solid advice, many wellness authors dramatize this a bit.
What Happens To Your Body When You Fast
Studies show us that fasting, the complete abstinence from food, provides many of the same health benefits as restricting calories. The study shows that fasting can help people lose weight, but we now know that it may also boost human metabolic activity, generate antioxidants, and help reverse some effects of aging.
Fasting may help people lose weight, but new research suggests going without food may also boost human metabolic activity, generate antioxidants, and help reverse some effects of aging. Researcher Takayuki Teruya said, “Recent aging studies have shown that caloric restriction and fasting have a prolonging effect on lifespan in model animals… but the detailed mechanism has remained a mystery.”
Not So Fast
Not all news on fasting is so great. On the flip, side studies show that severely restricting calories may significantly slow your metabolism. Again, muscle is living tissue, unlike fat, and requires energy to live. When we drastically cut calories, our body can go into “starvation mode” and begin breaking down muscle. Our bodies do this for two reasons: it uses the calories in the muscle for energy, and losing muscle slows the metabolism (daily caloric requirements). It’s our body’s way of attempting to maintain equilibrium.
On top of that extreme calorie restriction can lead to multiple other health problems such as fatigue, nutrient deficiencies, reduced fertility, disturbed hormone levels, weaker bones, and weakened immune defenses.
Calories: How Much is Enough? Too Much?
Contrary to popular belief, calorie consumption is not the only determinant of weight gain and loss. Not too long ago professors at universities were teaching that weight gain and loss was a simple equation of how many calories you’re intaking compared to how many you’re expending. Now we know several factors affect our weight, this simple formula doesn’t have all of the answers.
The government is heavily involved in establishing healthy guidelines for Americans and strongly advises that people never eat fewer than 1200 calories per day.
What Are Your Personal Caloric Needs?
Our bodies require energy all the time; even when we’re idle on the couch. This base metabolism is known as the Basal Metabolic Rate, aka BMR. Men usually have a higher BMR than women, and our BMR accounts for up to 70 percent of calories expended on an average day.
After age 20, BMR typically declines by 1-2% per decade, meaning that we have to work harder to burn off calories as we age.
The Rest of the Equation
The basic metabolic rate varies from person to person, and a lot of this has to do with fat free mass. This means that if you have more weight, but also more muscle compared to someone else, your body will burn more calories. Everyone’s body composition is a bit different, and this plays a role.
Around 70% of an individual’s total energy expenditure is your organs working to keep your body functioning. About 20% is attributed to physical activity that you put out, and the remaining 10% is expended when your body digests food.
The Impact of Calories From Carbohydrates
A food’s carbohydrates glycemic index (GI) is what tells us how rapidly it will raise our blood sugar. The glycemic index is a numerical value that describes a particular carbohydrate source’s impact on blood sugar levels.
Foods with a high GI create a massive spike of insulin. This insulin surge shuttles blood sugar into muscle and fat cells and can lead to low blood sugar, which has been shown to cause lots of nasty symptoms such as fatigue, blurred vision, headaches, and more. Further, insulin has been shown to create new fat cells, and signal existing fat cells to retain fat instead of releasing it for energy.
Glycemic Index Vs. Glycemic Load
While it is meaningful to know the glycemic index (GI) of foods in your diet, it is useless information if you don’t know the glycemic load (GL). The glycemic index tells us how much a single gram of any given carbohydrate source will increase blood sugar.
It is the glycemic load, however, which tells us how much the total carbohydrates we consume, will affect our blood sugar. Foods like high-sugar beverages and white rice have a high glycemic load, while carrots, cashews, and milk have a low glycemic load.
How Do You Figure it All Out; Already?
The whole idea is to consume foods that are able to be quickly digested through the bloodstream. Your body will have higher-functioning digestion if your diet primarily consists of fiber-rich fruits and vegetables and whole-wheat varieties.
If you have diabetes or are aiming to maintain steady blood sugar, it’s important to avoid foods like macaroni and cheese, pizza, and french fries. The glycemic formulas may sound complicated, but your judgment is likely better than you think.
The “Negative Calorie” Myth
The “negative calorie” food theory is bunk. This theory poses that some foods require more energy to break down and process than the energy it supplies in calories; resulting in a net energy deficit and, theoretically, results in weight loss. Most of these “negative calorie” foods are high in water and fiber and low in fat, like celery.
We could give you the study details, but we’re short on ink and daylight. There is no such thing as magical “negative calorie” foods. It is a beautiful thought though.
A study tracked participants for 24 weeks using a web-based dietary logging system. These participants were to record everything they ate. Simply keeping track of what they put in their mouths resulted in the participants losing weight.
Researchers of the study concluded that in this study, after the six month period, those losing between 5% and 10% were those who logged in their journal significantly more frequently during the study. The conclusion was that the frequency of self-monitoring correlated significantly to weight loss
Now That You Know About Counting Calories: Some Say “Don’t Do It.”
A recent study out of Stanford separated participants into two groups. Both groups were told to eat as much as they want, but one group was instructed to eat a low-carbohydrate, high-fat diet and was told not to drink soda or other sugary drinks, junk foods, or white bread. The other group ate a low-fat, high-carbohydrate diet.
After the year-long study, the results among the two groups were very similar. The low-fat group lost 12 pounds, and the low-carb group lost 13 pounds. What’s significant is that they ate as much as they wanted and still lost weight. This demonstrates that calorie counting may or may not be the way to lose weight.
Burning Calories with Cardiovascular Exercise
There are many types of cardiovascular exercise, and walking tops the list for a few reasons. It is easy for beginners to start walking vs. jogging. A 155-pound person walking at four mph burns about 167 calories every 30 minutes. If you really want to fry some calories in a hurry, vigorous stationary bicycling will burn 391 calories in the same 155-pound man in a 30-minute session.
Four 15-second sprints will burn as many calories over a 24-hour period as 30 minutes of moderate-intensity steady-state jogging. Rest at least 90 seconds between sprints.
Burning Calories With Resistance-Training
Resistance training not only burns 112 calories every 30 minutes but it also increases your metabolism for hours after your workouts burning calories at an elevated rate. With cardiovascular exercise, on the other hand, research shows that metabolism returns to normal shortly after a workout.
Muscle is living tissue and requires energy (calories) to survive. The more muscle you have, the more calories are needed just to keep your muscles alive. One study found that 24 weeks of weight training led to a 9% increase in men’s metabolism and 4% in women. This equates to about 140 more calories a day in men and 50 calories a day in women.
Ultra-Processed Foods Increase Appetite & Calorie Consumption
One report exposed inpatient subjects to either unprocessed diets or to ultra-processed diets for 14 days. The foods between the two groups were similar in calories, sugar, fat, sodium, fiber, and macronutrients. The subjects were allowed to eat as often and as much as they wished.
The group on the ultra-processed diet ate, on average, 500 more calories a day than the group on the unprocessed diet plan. In other words; something about highly processed foods makes you want to eat more than their unprocessed counterparts.