an empty plate, a set of cutlery and an empty glass

What are calories and what do they do?

What are calories and how many of them do you actually need to develop a healthy lifestyle?

You hear about calories all the time. How many calories are in this cookie? How many calories are burned by 100 jumping jacks, long-distance running, or fidgeting?

Calories are a way of keeping track of the body’s energy budget

A healthy balance occurs when you put in about as much energy as you lose.

If you consistently put more energy into our bodies than you burn, the excess will gradually be stored as fat in our cells, and you’ll gain weight.

If you burn off more energy than you replenish, you’ll lose weight.

So you have to be able to measure the energy you consume and use, and you do so with a unit called the calorie.

What is a calorie?

One calorie, the kind you measure in food, also called a large calorie, is defined as the amount of energy it would take to raise the temperature of one kilogram of water by one degree Celsius. It’s usually defined as 4.1868 joules.

How do calories work?

That energy is released during digestion and stored in other molecules that can be broken down to provide energy when the body needs it.

It’s used in three ways: about 10% enables digestion, about 20% fuels physical activity, and the biggest chunk, around 70%, supports the basic functions of our organs and tissues. That third usage corresponds to your basal metabolic rate, the number of calories you would need to survive if you weren’t eating or moving around.

How many calories do you need?

How many calories the average person requires each day, 2000 for women and 2500 for men. Those estimates are based on factors like average weight, physical activity, and muscle mass.

Variations in things like enzyme levels, gut bacteria, and even intestine length, means that every individual’s ability to extract energy from food is a little different.

So a calorie is a useful energy measure, but to work out exactly how many of them each of us requires you need to factor in things like exercise, food type, and our body’s ability to process energy.

Are calories good or bad?

Different foods, macro-nutrients and even combinations of foods, go through different metabolic pathways and can have vastly different effects on your digestion, nutrient partitioning, metabolism, hunger and the hormones that regulate your body weight and fat percentage.

Protein calories vs fat calories

For example, a protein calorie is not the same as a fat calorie or a carb calorie.

You’ve all heard the quote ‘a calorie is a calorie’, but is it true? According to Best-selling author and UCSF endocrinologist Dr. Robert Lustig, there are many reasons to think that that’s not the case.

What calories are good for diabetes?

Number one, obesity, and diabetes are not the same. Turns out there are countries that are obese without being diabetic, such as Iceland, Mongolia, Micronesia, and there countries that are diabetic without being obvious, such as India, Pakistan, and China.

The bottom line is that is not about obesity because ‘a calorie is NOT a calorie’, it’s about insulin and insulin resistance.

What is insulin resistance?

Insulin resistance being the phenomenon where your insulin doesn’t work well so your pancreas has to make more and it’s insulin who drives all those metabolic diseases like heart disease, dementia, hypertension or diabetes.

So, in fact, it’s not about the calories it’s about the insulin response that those calories cause and the insulin response is very specific to the food consumed.

Processed food it’s sure laden is the most egregious in terms of driving insulin resistance and all of these chronic metabolic diseases.

How are calories important for your health?

The most important thing that can be told is that your body runs on nutrients, not calories.

Empty calories like pastries, sugars, processed foods and so forth do nothing to feed your cells and thus, your body and brain become hungry an hour or two later.

Calories fuel the body

The “fuel” doesn’t last very long. However, nutrient-dense foods such as proteins, healthy fats, healthy carbohydrates, and vegetables give your cells what they need, to convert the food into energy, instead of being stored as fat.

They’ll increase your metabolism by producing good, youthful hormones, according to Dr. Sam Robbins.

Are calories created equal?

If calories were all created equal, then people might all simply exist on a set number of calories from ice cream.

Foods are not made up of calories alone, but rather they are complex mixtures in terms of fiber, nutrients, and additives.

This can have a vastly different effect on the hormones that control hunger (leptin) and those that direct our bodies to either burn or store fat (insulin).

people toasting with beer and a table full of food

What calories are good for weight loss?

Complicating things is the fact that our bodies are naturally programmed to defend our fat stores as a biological means of protecting against long-term starvation.

In general, you want to focus on foods that have a lower glycemic index versus foods that have a higher one, so what that means is how much it’s going to affect your blood sugar, so how much of that hormone insulin you’re going to release.

What is the glycemic index?

For example, something that’s pure sugar, or white bread or white pasta are refined processed carbohydrates, and they’re going to have high glycemic indexes.

In general, foods that are less processed such as whole foods, lean protein, healthy fats and grains that are unprocessed are going to have lower glycemic indexes.

They’re going to affect those hormones that store fat less than the plain old sugar items also they’re going to provide you with nutrients. You’re gonna feel good, you’re going to just be a healthier person.

Case study

A study published in The American Journal of Clinical Nutrition points to the effects of metabolizable energy and diet-induced changes in energy expenditure indicate that having 2 groups of subjects consume 2 different energy-restricted diets could introduce a different energy imbalance.

Feeding diets that induce a difference in energy expenditure can introduce a difference in energy balance and thus a difference in weight loss.

How are calories burned?

Your fat tissue is full of important biological molecules called lipids.

Long and stringy compounds of hydrogen, carbon, and oxygen are great at storing energy in their chemical bonds.

When the molecules are broken apart they release the energy stored in their bonds. This process is normally called ‘burning fat’.

How is the process of burning fat?

But when you “burn fat” where does that material go?

A recent survey of doctors, dietitians, and physical trainers revealed that even the experts in fat loss didn’t know the answer. Although they thought they did.

More than 50% of the respondents thought that when you burn fat, all that mass is simply converted into energy and lost as heat. It’s a common misconception, but that’s NOT possible.

The basic principles of chemistry are applied

I mean just because you don’t like something doesn’t mean that the laws of chemistry don’t apply to it and one of the basic principles of chemistry is the conservation of mass.

This just means that the same amount of material always comes out of a reaction as goes into it.

Even if that reaction happens to generate heat, you’ll wind up with the same number of each kind of atom that you started with.

So, when you break up those lipids in your fat cells and release their energy all of that hydrogen, carbon, and oxygen in those molecules will still be there afterward.

Where does the mass go when you burn fat?

But if you burn a lot of fat, where does the mass go?

Turns out, you exhaled it.

Biologists at the University of New South Wales recently did an atom by atom breakdown of where the mass of your fat goes after it’s burned in your body.

They found that for every ten kilograms of fat that you burn, you have to inhale 29 kilograms of oxygen to metabolize or break down the fat and release its energy and the process of breaking down that much fat produces 28 kilograms of carbon dioxide and 11 kilograms of water.

You exhale the fat away

So for every kilo of fat that you burn in your body, more than 80% of that mass is lost as carbon dioxide that you breathe out.

The other 20% you lose as water in your urine or sweat or depending on how hard you work out, with your tears, but if you do the math, you will see that all the mass in that fat-burning reaction has been conserved.

Calories in vs calories out

There is a fundamental flaw in the energy balance equation, which says that: body fat = calories in – calories out.

So people assume that if they reduce the number of calories they take in is going to reduce their body fat.

But the question should be if you reduce your calories taken in do your calories that your body expends stay stable? And the answer is no.

Case studies

There are studies done in 1917 where they take volunteers and they reduced the number of calories that they eat by roughly 30%.

Then they measure their basal metabolic rate, which is the number of calories that they’re burning on a day to day basis, and what they found is that the body had reduced its energy expenditure by about 30 percent.

So if you’re taking 30% fewer calories in and your body is using 30% less then you’re not going to lose any body fat.

a woman wearing jeans too big for her

How many calories do you need to consume to lose weight?

This is a very recurrent question.

A lot of people thinks that applying the rule of body fat, or put in other way consuming fewer calories, they are going to shed the pounds, but it does not work like that.

The matter is that you need to consume fewer calories than you burn if you want to lose weight. How fast that will happen depends on how much you reduce your calorie intake, but it’s not a one-size-fits-all type of situation.

Not a one-size-fits-all type of situation

Your ideal calorie intake depends on your age, height, size, lifestyle, gender, and overall health. There are some general recommendations.

The 2015 to 2020 Dietary Guidelines for Americans advise men to consume 2,500 calories a day, while that number for women is 2,000, little kids should take in about 1,500 a day, while adolescents require a lot more especially boys, for instance, an active and rapidly developing male teen from 16 to 18 years old needs roughly 3200 calories per day.

As people get older they need fewer calories

As people get older they need fewer calories, the reason for that is their metabolism slows down so they need less energy.

That’s why women aged 19 to 25 need 2,000 calories a day but that number drops to 1600 after they turn 51 years old, according to the Centers for Disease Control and Prevention.

How many calories do you need for muscle gain?

Here again, there is not a single answer, the number of calories you need to take to gain weight will differ from one person to another.

First thing you need to find out what your maintenance calories are.

What are maintenance calories?

Maintenance calories just means the calories that you need to intake so that your weight is constant, you’re neither gaining not losing, its kind of hovers around at a center point , and from there you can add about 500 calories to bulk and put on some muscle or diminish 500 calories for cutting or lose weight.

How many calories are burned when exercising?

There are many exercises you can do to burn calories fast such as cycling, swimming, running or walking.

But how many calories do you actually burn practicing these activities?

How many calories do you burn cycling?

There are various ways of calculating how many calories you burn when cycling.

A power meter is a great way to work it out. However, you can also do the math with a formula based around your heart-rate.

There are many variables to consider too, such as fatigue, a naturally low heartbeat, etc. Oh, and let’s not forget, you are even burning calories when resting/recovering.

Measure the power is the key

Pedaling a bike requires power, which is measured in watts.

You can roughly assume that producing one watt of power for an hour will burn about four calories.

It doesn’t sound like much, but so, if you go at 10 miles per hour on a flat road, it will require about 40 watts, at 15 mph about 100 and at 20 mph on a flat road, about 210 watts.

So riding 10 miles in an hour requires about 140 calories. 15 mph about 350 calories, and 20 mph about 700.

How many calories do you burn swimming?

Swimming is one of the all-around best exercises that you can do.

Whether that is for muscle building, muscle training or calorie burning and cardio.

man swimming in open water

30 minutes of light basic strokes, just going around a pool, with a weight of a hundred pounds and you could burn around 180 calories, if you’re at 150 pounds then you can burn around 270 calories, at 200 pounds, it jumps up quickly here does about 362 calories, at 250 pounds 450 calories and at 300 pounds about 550 calories.

How many calories do you burn running?

Remember that this is just a guideline, and these numbers can vary depending on the conditions you are running in and by how fast you are running.

100 pounds for 1 mile about 65 calories burnt, 150 pounds for 1 mile about 100 calories burnt, 200 pounds for 1 mile about 130 calories burnt, 250 pounds for 1 mile about 165 calories burnt.

Kg. and Km.

50 kilograms for 1 kilometer about 45 calories burnt, 75 kilograms for 1 kilometer about 70 calories burnt, 100 kilograms for 1 kilometer about 90 calories burnt, 125 kilograms for 1 kilometer about 115 calories burnt.

How many calories are burned when walking?

A 160-pound person walking briskly for an hour can burn as many as 277 calories.

Even walking at a 2 mile per hour pace you could burn 183 calories in an hour.

Are calories being burned while sleeping?

People burn calories when sleeping, and those who have more muscle mass in their bodies will burn more calories.

An American Journal of Clinical Nutrition study found that well-rested people burn 20% more calories after eating than those who don’t get enough sleep.

An average woman weighing about 135 pounds, although it may not sound like a lot she’s burning 56 calories an hour.

A man of about 190 pounds, he can burn about 80 calories an hour.

How many calories do you need during pregnancy?

A baby is small and therefore has small calorie needs during the first trimester.

During the second-trimester mom’s calorie needs to be increased by 340 calories per day, and during the third trimester, this increases to 450 calories per day, based on your pre-pregnancy BMI.

If you are in normal, healthy weight, you should aim to gain about 15 to 25 pounds during your pregnancy.

pregnant woman wearing a black top and pants

How many calories do you need when breastfeeding?

A woman who’s exclusively breastfeeding needs to eat 400 to 500 calories each day above and beyond her own body’s requirements.

If the baby begins to be supplemented with formula, and the mother is actually nursing less, or as the baby starts eating solids, then the mother’s extra caloric requirement may go down a little bit.

So let’s say that your basal metabolic rate is 1500 calories, you are going to burn more calories throughout the day by doing activities, like chasing a toddler or exercising daily, and so you may be able to get away with 1800 to 2000 calories each day to maintain your weight.

How many calories does fruit have?


A banana contains about 80 calories.


An apple contains about 45 calories.


A plum has about 20 calories.


One pineapple contains about 42 calories.


One pear contains about 48 calories.


A peach has about 36 calories.


An orange has about 48 calories.


One clementine contains about 20 calories.


100 g of grapefruit has about 67 calories.


100 g of blackberries has about 28 calories.


100 g of cherries has about 40 calories.


One kiwi contains about 25 calories.


An apricot has about 17 calories.


A mango contains about 59 calories.


One lemon has about 14 calories.


100 g of strawberries contains about 33 calories.


100 g of watermelon contains about 30 calories.


There are just about 25 calories in 100 grams of cucumber.


100 g of avocado contains 190 calories.

a bowl of grapes

How many calories are contained in food?

chicken breast

A cooked 3.5 oz. skinless chicken breast contains 165 calories.

Chicken breast with the skin on contains almost 35 extra calories.


100 g of beef has about 250 calories.


100 g of catfish has about 100 calories.


100 g of salmon has about 180 calories.


100 g of sardines contains about 170 calories.


100 g of tuna has about 95 calories.


100 g of anchovies has about 275 calories.


100 g of trout contains about 79 calories.


An egg contains about 78 calories.


100 g of mushrooms has about 22 calories


100 g of cooked white rice contains about 130 calories.

How many calories are in alcoholic beverages?

The calorie content is largely based on the ABV % and a stronger beer or wine will have more alcohol in it and therefore more calories.

Jack Daniels's whisky bottle
detox from alcohol

Calories in a beer pint

Fosters Pint: 193 calories

Grolsch Pint: 215 calories

Amstel Pint: 227 calories

Kronenbourg Pint: 244 calories

Guinness Pint: 210 calories

Calories in beer bottles

Heineken Bottle: 139 calories

Peroni Bottle: 142 calories

Stella Artois Bottle: 115 calories (smaller bottle)

Corona Bottle: 148 calories

San Miguel Bottle: 140 calories

Calories in a shot of spirits

Whiskey shot: 72 calories

Vodka Shot: 64 calories

Tequila Shot: 69 calories

Rum Shot: 64 calories

Gin Shot: 73 calories

Calories in a wine glass

White Wine 175 ml Glass: 141 calories

Red Wine 175 ml Glass: 148 calories

Rose Wine 175 ml Glass: 138 calories

Calories in wine bottles

White Wine Bottle: 605 calories

Red Wine Bottle: 625 calories

Rose Wine Bottle: 590 calories

Calories in cocktails

4 oz. of margarita: 168 calories

Gin and tonic: 142 calories

Vodka soda: 97 calories

4 oz. of champagne: 84 calories

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