Food Topics Health Trends

Go Forth and Diet: Why Do Calories Matter?

Wondering how to lose weight? This is the first part of a multi-part series where I break down the different parts of a diet and explain how they play a role in weight management or loss.

Weight management is something that people tend to struggle with. By the day it seems more and more fad diets go on the market that get proven ineffective or potentially dangerous (read more about them here). Sometimes there is no science backing up what the diet or gadget claims (anything from smelly waxes, incense, magnets etc.), which can lead to fatigue with dieting and exercise when results are not achieved. This is going to be the first in a series of posts where I discuss various aspects of diets to inform you that health is more than just eliminating food groups, or an explanation on why diets are interesting.

To start, I need to define what a Calorie is. The definition of a Calorie is the amount of energy needed to raise the temperature of one gram of water one degree Celsius. Quick online searches might show you “How many Calories in a can of gasoline,” or in uranium. Your body cannot process these for energy very well (especially uranium, which is a rock). In terms of food and nutrition, the only Calories that matter are the ones your body can process.

If all that is confusing, let me explain this in another way. Think of a Calorie as an energy unit your body needs to stay alive. If you use (or burn) more than you eat every day, then you should expect some weight loss. Eat more than you use, and you should see it stored (most visibly as fat) Everyone has a different amount of Calories they need a day to maintain a healthy weight. Typically this is around 2000 Calories/day. If you are interested in how many Calories you need, click here. This is based on a variety of factors, such as age, sex, and activity level. For example, I am a 25 year old, six-foot tall 155 pound active male, meaning my Caloric needs per day are around 2500 Calories/day.

The way your body gets Calories– or energy– is from eating food and using stored energy. Different foods have different Calorie levels per gram. Protein and carbohydrates have four Calories per gram, fat has nine calories per gram, and alcohol has seven Calories per gram. So what does this look like in reality? One Tablespoon of fat (i.e. olive oil, butter, coconut oil) has somewhere between 100-120 Calories. To get this same amount from carrots, you would need to eat about 2.5 cups. Why are they different? For one, your body can get more energy from a molecule of fat than it can from a molecule of carbohydrate. Second, carrots are full of water and fiber, which increases its volume without increasing Calories (I will explain what fiber is in further detail in a later post).

How much fat, protein, and carbohydrate do you need per day? The typical healthy range in terms of Calories/day given is 45-65% from Carbohydrate sources (grains and cereals, fruits and vegetables), 20-35% from fat (oils, butter, margarine, salad dressings), and 10-35% from protein (meat, cheese, milk, tofu and other meat replacements). These percentages of carbohydrates, fats, and protein helps to ensure there is enough energy to keep organs and muscles working, providing the building materials to make new cells, and mobilize different nutrients to different areas in the body. To see a more detailed breakdown of what is recommended per day, click here.

Why do fad diets (i.e keto, paleo, most diets in magazines or online) work? Most diets that people are interested in are for weight loss. Most of these diets will recommend reducing or removing different components from the diet, whether it’s fatty foods, high carbohydrate foods, or limiting times when you should eat all have one thing in common: they attempt to reduce how many Calories your body has available or can use per day. The keto diet promotes a low-carb, high fat, and moderate protein diet to change the energy source the body uses, however this has not been seen to work long term, and many that go off the diet see the weight return (this diet combines overall Calorie reduction by limiting Calories and metabolism shifts similar to what is seen in starvation). Intermittent fasting reduces the Calories you consume by limiting when meals can happen and/or by skipping entire meals or snacks.

How much do you actually need to reduce to achieve healthy weight loss? It’s recommended to not lose more than 1-2 pounds/0.5-1 kg per week, meaning any diet that promotes rapid weight loss that is not prescribed by a doctor or dietitian can be dangerous, or leads to weight loss via dehydration. Healthy weight loss ensures you are getting enough nutrients while losing weight. Weight loss of 1-2 pounds/week averages a Caloric reduction of about 500 Calories per day. This sounds like a lot, however a variety of different small changes per day can add up. Not drinking a 20 oz soda every day can save you nearly half of this (231 Calories, all from carbohydrates) or limiting alcohol can also add up (one beer averages around 200 Calories from carbohydrates and alcohol). Drinking black coffee, or with a small amount of milk and sugar, can save you a large amount of Calories when compared to mixed coffee drinks (these can range from around 100 Calories per drink to around 1500 Calories!) or energy drinks (sugar free options have low Calorie amounts, while sugared drinks have up to 160 Calories per serving, with many containers having nearly two servings per can).

Increasing fruits and vegetables while decreasing fats can also add up to variable amounts of Calories. Fruits and vegetables are low in Calories because they are high in water and fiber, which fills you up without giving your body a whole lot of energy. Where many people fail here is adding a large amount of dressing, sauces, or frying them. Using dips, sauces, dressings, or frying can be a good way to start eating fruits and vegetables to get accustomed to them being present in the diet, but in terms of weight loss or management, these can lead to weight gain if you’re not careful.

Often, a good first step for encouraging weight loss comes from choosing Calorie free drinks (water, black coffee, plain tea), and increasing fruits and vegetables over other other foods (fruits and vegetables are high in nutrients and low in Calories). This doesn’t mean you can’t have things like beer or soda either. If you want to try to manage your Calories, instead of having two beers, have one. Instead of a 20 oz soda, have an 8 oz soda. One of my college professors would mix a normal 12oz soda with a 12 oz diet soda, which would last him two days. This would be like drinking 6 oz of soda instead of 12.

For our intents, a Calorie is a unit of energy that your body can use. Calories come from carbohydrates, protein, fat, and alcohol. If weight loss is your goal, Caloric restriction is proven to be the most effective and healthy way to lose weight. This is effective across many diets that promote weight loss. Reducing Calories can be from choosing different options, such as water over soda or alcohol, or increasing fruits and vegetables at meals and snacks. A diet adequate in protein, carbohydrates, and fat provides enough materials to build healthy cells and the energy to run them. The trend that many diets follow that promote weight loss come from Caloric restriction.

Any further questions? Any interesting experiences with different diets you’d like to share? Any cool meal ideas? Feel free to comment them!

By The Nutrition Punk

I am a dietitian living in Portland, Oregon. I write about a variety of nutrition and heath topics, with the goal of improving people's understanding of food and nutrition so they may be empowered against all the misinformation that is out there.

3 replies on “Go Forth and Diet: Why Do Calories Matter?”

[…] CICO- or Calories In/Calories Out- is another way to look at healthy eating and weight loss. The idea is that to lose 1lbs of fat, you need to shave 3500 calories from your diet. This is done over a week-long period, meaning that each day you must shave off only 500 calories per day. If you want to learn more about calories, you can read another blog post I wrote here. […]


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