What if I told you that we know exactly what it takes to lose weight? As a matter of fact, we've known for well over 100 years and it has been proven time and time again in countless peer-reviewed research studies. There has never been a single diet trend that has worked without it. And we have yet to find any diet theory that has been able to disprove this one basic principle of weight loss. It's not a food or type of food, and it does not involve any special ingredients or supplements.
Have I peaked your interest yet?
The single most important factor for weight loss is calorie control, period. It is basic biology and also physics. If you eat less calories than your body needs you will lose weight. No matter if you are primarily burning fat, carbs or protein for fuel, it is impossible to lose weight without cutting calories. And the same concept applies for weight maintenance and weight gain.
That's right, the best thing you could possibly do to help yourself lose weight is to control your calories - by either eating less or moving more. Every diet that we know of only works if calories are controlled. And although we don't recommend it, you can even lose weight eating junk food if your are cutting calories overall. If you don't believe me, take it from a professor who wanted to prove this theory by losing weight on a soda, cookie and chip diet. (1). Or this guy who lost 27 pounds eating Twinkies.
Bottom line: Learn how many calories you need to eat to lose weight and stick to it!
At the simplest level, your body runs off energy in the form of calories from foods and beverages. Calories = energy. And you need this energy to fuel your daily needs and to just plain survive. If you stop calories, you will eventually die.
So what does survival have to do with losing weight? Well, because calories are so important for living, your body has a way to store them as muscle and fatty tissue - which is also the exact type of weight you are able to lose, gain or maintain. This storage form acts as a reserve fuel for times you are not getting calories directly from food, and as a safety measure just in case you aren't able to eat again for a while.
If the amount of calories you eat is equal to the number of calories you burn, you will maintain your current weight. If you eat less, you will use more reserve fuels for energy and lose fat and/or muscle weight. And if you eat more, you store more reserve fuel and gain muscle and/or fat. This is the calorie balance equation for weight management: calories in versus calories out.
There is no pill, special diet or food that is able to hack your metabolism and change this basic formula. No matter how much fat or how many calories you burn for fuel, you cannot lose weight or lose fat unless you eat less than what you burn.
What is a Calorie?
When it comes to nutrition, there is no single discovery more valuable than a calorie as it relates to energy intake and expenditure. Calories allow us to quantify our food, compare different foods and manage individual nutrition and fitness needs. But what exactly is a calorie?
Technically speaking, a calorie is the amount of energy needed to raise the temperature of 1 kg of water 1 degree Celsius. Or in other words, it is a unit of measurement that tells us how much energy is in our food. Initially, calories were measured by placing a food item in a sealed container and submerging it in water or burning the food. Today, calories are estimated using the food macronutrient breakdown, or in other words, the amount of carbs, fat and protein a food contains (2).
Calories have long been used as a measurement of heat, dating back to the early 1800's. But what we know and recognize as a food calorie today was not established until sometime around the 20th century (3). To this day, calories remain the most efficient way to measure energy intake and output, and the best way we know of to directly affect weight management.
Food and drinks are made up of macros - carbohydrates, protein, and fat - that supply all of the calories we eat. Each macro has a different role when it comes to health and nutrition and also provides a different number of calories per each gram. Because macros play a role in your health and energy intake, tracking your macros is an efficient way to count calories and balance your nutrition intake.
Carbohydrates and protein have roughly four calories per gram and fat is the most calorically dense macro at nine calories per gram. Alcohol is also technically a macro since it provides calories, but it's not important for nutrition in the same way protein, fats, and carbs are. And just like fat, alcohol is fairly calorie dense - each gram has seven calories.
Micronutrients, such as vitamins and minerals, also play a role in overall health and weight management but they do not directly contribute to calorie intake. In other words, you don't get any calories from the vitamins and minerals that you eat or drink. And even though many micronutrients are involved in metabolic processes that help you get energy and can sometimes make you feel more energetic (I'm looking at you B12), they cannot increase your energy alone, you still need calories from macros for this.
How Many Calories Do You Need?
Calorie needs are completely individualized which is part of the reason why calorie control works so well for weight loss - there is no one size fits all approach to how much energy your body needs. Calorie needs can vary depending on age, height, gender, weight, percent lean muscle mass and level of activity.
Your daily calorie needs are made up of four major components, BMR, NEAT, TEA and TEF. Together, these comprise your total daily energy expenditure (TDEE), which is a fancy way of saying how many calories you burn each day based on your lifestyle, physical activity, and personal needs.
BMR: What is Basal Metabolic Rate?
Your daily bodily functions - like your heartbeat, brain power, and breathing, all need a certain number of calories to work. This basic amount of calories is also known as your basal metabolic rate (BMR) or resting metabolic rate (RMR). This is the bare minimum of energy you need each day, if you never left your bed or moved around, and accounts for 60% to 70% of your daily calorie requirement.
TEA and NEAT: Activity Energy Expenditure
Assuming you will move around at some point during the day, you will also need to consider calories burned from activity. This includes non-exercise activity thermogenesis (NEAT) and your thermogenic effect of activity (TEA). NEAT is essentially basic daily movements, including how much you fidget, whereas TEA is the effect of exercise or more strenuous physical activity. Combined, these two make up roughly 20% to 35% of your energy needs.
You can calculate your calorie burn using an online calorie burn calculator, or you can estimate your needs using an activity factor (AF). Based on how active of sedentary you are each day, use one of the following, or perhaps somewhere in between:
- Sedentary (AF of 1.2) - Little to no exercise. Use this activity factor if you sit at a desk most of the day and do not plan to exercise.
- Lightly Active (AF of 1.375) - Light exercise or training 1 to 3 days per week. Use this activity factor if your exercise regime includes walking and other activities that do not cause you to break out into a sweat.
- Moderately Active (AF of 1.55) - Moderate exercise 2 or more days per week. Use this activity factor if you are working out a couple days or more each week and breaking a light sweat.
- Very Active (AF of 1.725) - Hard exercise 3 or more days per week. Use this activity factor if you are working out multiple days a week and breaking into a full sweat.
- Extremely Active (AF of 1.9) - Working out 2 or more times a day. Use this activity factor if you are a high-performance athlete, training multiple times a day, or performing a daily job or routine that requires constant strenuous activity.
What is TEF?
Your total daily energy expenditure is also affected by something called the thermic effect of food (TEF), also called diet-induced thermogenesis (DIT). TEF or DIT accounts for only a small portion, 10% of your total TDEE, but it is still worth noting.
Digestion in itself requires energy - meaning it takes calories to turn calories from food into usable energy by the body. And depending on the type of macro you consume, you can cause your energy expenditure to slightly increase the TEF.
Through TEF, eating macros in isolation would cost you the following percent of calories from the food to be used for digestion (4):
- Protein requires 20–30%
- Carbohydrates require 5–10%,
- Fats require ~3% or less
Mixed dishes, which is closer to how we typically eat, average about 10% of calories lost to TEF.
Calculate Your TDEE
Once you have your BMR and activity factor, estimating your daily calorie intake is easy. Simply multiply the two together to get your TDEE.
TDEE = BMR x AF
Because TEF is such a small portion of your TDEE, it is not necessary to consider when calculating your overall calorie needs. But it may still be an important factor when considering what to eat for weight loss.
You can also use an online calorie calculator to estimate your daily calorie needs.
How Many Calories Should You Eat to Lose Weight?
I know what you're thinking, cutting as many calories as possible is the best way to quick weight loss. But trust me on this, you are going to be much happier and more successful in the long run if you only cut 15 to 20% of your calories or less. Starving yourself might work temporarily, but it certainly isn't going to be sustainable or even enjoyable for that matter. And you may end up gaining all the weight back and then some.
Start with one of the following for at least three weeks and then reassess your needs:
Sustainable Weight Loss = TDEE x 0.85
Fast Weight Loss = TDEE x 0.8
If you find that after dieting for some time, you are no longer losing weight, it might just be time to give yourself a break. Take a couple weeks off your diet and let your calories creep up just a little. If you've lost some weight, you probably have to recalculate a new TDEE to maintain your new normal. And then after a little bit of time adjusting, you can get back to cutting calories if you still need to lose more weight.
Whatever you do, don't rush it or push your body too hard. Remember this is survival fuel we are talking about here. And your personal wellbeing is just as, if not more, important than the number on the scale. You will reach you goals, you will make progress and you will see results, you just need to be consistent and give yourself time.
How Many Calories Are in a Pound?
Wondering how many calories you need to cut in order to lose one pound? Well, there are roughly 3,500 calories in a pound of fat, so you would need to cut this amount from your diet through food or exercise to lose one pound.
This number will also give you a good gauge of how fast you are able to lose weight since there are only so many calories you can cut or burn each day. If you spread out 3,500 calories throughout the week - 500 calories a day - you can expect to lose about a pound a week. But again this depends on many individual factors and is not a perfect science.
How to Make Your Calories Count
Your body needs energy to live, but you also need good nutrition to live well, and longer. While the quantity of what you eat will determine overall weight loss, gain or maintenance, the quality of what you eat also plays an important role. The overall balance and nutrition of your diet can affect the type of weight you lose, gain or maintain. If your macro balance is out of whack, you could be storing more fat or losing muscle mass, which can hinder your overall efforts.
In addition, eating more nutrient dense foods may help you lose more weight and control hunger (5). When your body is not getting the nutrition you need or is deficient in key nutrients, it signals to your brain that you need to keep eating, regardless of how many calories you’ve consumed. Make your calories count and choose the most nutrient dense foods for optimal and healthy weight reduction.
Weight loss is a numbers game, but there are a few things you can try to make your journey more bearable and give you even better results by either focusing on the types of foods you are choosing, getting your mental health in check, and opting for the most efficient forms of exercise for weight loss.
To easily track your daily calorie intake and overall nutrition for FREE, download the Trifecta App!
Calories do count. Kinsell, Laurance W. et al. Metabolism - Clinical and Experimental , Volume 13 , Issue 3 , 195 - 204
Nutritional Journal. 2010. 9:51. “Changing Perceptions of Hunger on a High Nutrient Density Diet. Nutrition Journal. 2010;9:51. doi:10.1186/1475-2891-9-51.
WHO World Health Report 2002: Reducing Risk - Promoting Healthy Life. Geneva: Switzerland, 2002.
A. Luke, D.A. Schoeller. Basal metabolic rate, fat-free mass, and body cell mass during energy restriction. Metabolism, Volume 41, Issue 4, 1992. Pages 450-456, ISSN 0026-0495. https://doi.org/10.1016/0026-0495(92)90083-M.
G Dulloo, A & Jean, Jacquet & Girardier, L. (1996). Autoregulation of body composition during weight recovery in human: The Minnesota Experiment revisited. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 20. 393-405.
Drenowatz, Clemens & Hill, James & Peters, John & Soriano-Maldonado, Alberto & N. Blair, Steven. (2016). The association of change in physical activity and body weight in the regulation of total energy expenditure. European Journal of Clinical Nutrition. 71. 10.1038/ejcn.2016.228.
Schoeller DA, Thomas D. Energy balance and body composition. World Rev Nutr Diet 2015; 111: 13–18.
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Dulloo, A.G. & Jean, Jacquet. (1998). Adaptive reduction in basal metabolic rate in response to food deprivation in humans: A role for feedback signals from fat stores. The American journal of clinical nutrition. 68. 599-606. 10.1093/ajcn/68.3.599.