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In this article:
What Are Calories
Fuel For Your Muscles
How many calories in Fat, Carbs, Protein, Alcohol
Exercise; High or Low Intensity to Burn Fat
Summary For Fat Loss


Daily Caloric Requirements For Fat loss, Staying Lean, And Exercise/ Training: Go here in this article to learn about fat loss


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Quick Estimate: Body weight in pounds X 10 = minimum calories per day required for zero activity. Add 500 calories for minimal daily activity (not exercise). Add another 300 calories for 1 hour of easy to moderate exercise. Athletes and intensive exercisers need more. Eg. Weight 170lb. 170 x 10 = 1700. 1700 + 500 = 2200 calories. 2200 calories are needed for a day with no exercise and minimal activity, 2500 calories are needed for a day with about one hour of exercise in this example using a 170 lb person. A 170 lb person working out every day could need up to 3000 to 3500 calories per day. This is based on a non-overweight person. If overweight, reduce your total calories from this formula by 10% and start from there. These are estimates, not absolutes.

Another Popular Quick Estimate: 30 to 40 calories per kilogram of body mass per day. (13 to 18 calories per pound). The lower number is more suited for less daily activity and fat loss; the higher number for including about 1 hour of daily exercise and maintaining weight. These are estimates, not absolutes.

A more detailed estimate, but still an estimate:
Green depicts athletic or very active person

  • Protein 1.2 -2g per kg body weight

    0.8 - 1.0g/ day sedentary.
    1.5 - 1.7g/ day building muscle mass through weight training and or daily aerobic exercise.
    1.8 - 2.0g/ day athletic conditioning- extensive aerobic endurance or mass building. (Click here: Article on the myth of extra protein to gain muscle)

  • Carbs 3 - 5 g per pound

    No exercise 2g per pound.
    Training one hour per day 6-7 g per kilo/ 3g per pound.
    Two hours per day 8-9 g per kilo/ 4g per pound.
    Three hours per day 10-11g per kilo/ 5g per pound.

  • Fat 1g per kilo/ .5g per pound (.1g less when on a fat loss program)

Generally the ratio of daily food intake should be (reflected in above guideline):

  • Carbohydrates: 60 - 65% for active/ very active people. 55% For inactive people
  • Fat: 20 - 30%: Females require a little more fat in their diet than males. Youth up to about age 18 require a little more fat in their diet than adults. 30% is still the maximum for all populations though.
  • Protein: 15 - 20% Extremely active persons involved in sports require a little more protein than inactive people. Specifically those training to increase muscle mass or those involved in extensive endurance sports like marathon and triathlon. Long distance runners require as much or more protein than bodybuilders.

These are estimates, not absolutes.

The most accurate method for determining basic caloric needs: Contact a university exercise physiology department and inquire about a resting metabolic rate test. The test involves remaining seated for 10 to 15 minutes with a hose in your mouth into which you breath freely. The hose is connected to a machine called a metabolic cart. It measures the difference between oxygen breathed in and oxygen and carbon dioxide breathed out. This measurement combined with a few others allows the technician to provide the most accurate estimate of how many calories you need in one day.

What are calories, and why do calories matter?

A calorie is a unit of heat energy. It is the amount of energy required to heat 1 gram of water 1 degree Celsius at sea level. A Kcalorie (kilocalorie) is the amount of energy required to heat 1 kilogram of water 1 degree Celsius at sea level.

The Kcalorie is the unit we use for food energy, but often the "K" is removed, as is done for the remainder of this article and throughout this web site. This unit of heat energy is used to measure energy consumed (food in) and expenditure (physical activity) in humans because heat is the primary byproduct of metabolism. Our cells are constantly busy using energy (measured in calories), which gives us our body heat. We get even warmer when we exercise. Scientists measure this heat in calories to determine energy expenditure. When we eat too much we store the extra calories as fat.

Actually, since a calorie is a unit of heat energy, and we don't really store extra heat per se, the fat we store has potential energy which is only measured as calories when it is later used for energy. We store actual fat, but we refer to it in terms of it's energy potential expressed in calories. One pound of stored body fat has an energy potential of 3500 calories, so we can say "one pound of fat" or, "3500 calories of fat"; they are both ways of describing the same amount of fat. The dual-description of calories and mass also applies to carbohydrates and protein.

Eating too much and not exercising enough is the leading cause of obesity. To lose fat we need to burn off more calories, or energy than we eat. The actual energy compound used by muscles is ATP (adenosine triphosphate). ATP is made from fats and carbohydrates through complex chemical pathways.

The fuel for your muscles is ATP

  • Fats cannot be used alone to make ATP, carbohydrates are required in the process.
  • Carbohydrates can be made into ATP without fat.
  • Fat can only be made into ATP aerobically. (Anaerobic activities like sprinting and lifting weights do not use fat as a fuel source).
  • Carbohydrates can be made into ATP aerobically (with oxygen) or anaerobically (without oxygen, with increased muscle acidity being a major byproduct).

About 5 to 10% of our fuel comes from protein, this ratio remains constant and as such is typically not mentioned. The one exception to protein as a fuel source is starvation or consuming too few carbohydrates. In this case lean muscle tissue is broken down and used as fuel. This is a survival mechanism, the same survival mechanism that many fad diets promote using to drop weight. However the "weight" in this case is your muscle, water, and some from fat, the muscle and water loss being unhealthy.

Caloric Value for Substrates:

Protein 4.3 calories per gram
Carbohydrate 4.1 calories per gram
Fat 9.3 calories per gram
Alcohol 7.0 calories per gram

To the astute reader you'll notice that if you multiply the 9.3 calories per gram in fat by 454 to obtain calories per pound (454 grams = 1 lb) you will get 4222. That's right, a pound of fat has about 4222 calories, NOT 3500. So why do we always read about 1 pound of fat having 3500 calories? Surprisingly many dietitians, doctors, and trainers are dumbfounded by this question.

The answer is there is a difference between dietary fat (fat that we eat) and adipose tissue (the tissue where fat is stored in our bodies). A pound of human adipose tissue contains substances other than fat such as connective tissue, water, and protein, which makes up about 15% of the fat mass.

A pound of dietary fat is supposed to contain around 4086 calories. I say around because although there is a common reference to 9 calories per gram of fat, this is the rounded down reference, we can also find references of 9.25 calories per gram of dairy fat and 9.5 calories per gram of animal meat fat.

Using the USDA food database reference 454 g (1 lb) of butter has 3255 calories.

So not even butter, which most would assume is the perfect example of "pure fat", is not pure fat, it contains water and a small amount of protein. According to this reference, 454 grams of butter has 368.24 grams of fat. 368.24 X 9 = 3314.16, which is not the 3255 calories listed above, nor 3500 calories, nor the 4086 number we got before.

Can we really find a food calorie reference that matches at least one standard reference? leave it to me find out what few others have the curiosity to find out!

There you have it. One pound of pure lard has 4086 calories.

So really what we learn here is that there is a range of references for the caloric value of fats whether in dietary form or stored as body fat. The differences are in which formula value is used, and how much "other" stuff (water, protein) there is in the kind of fat you are measuring.

Confused? That's probably why the common reference is pared down so much - it's easier to think about when we only have two references, the dietary fat reference of around 9 calories per gram, and stored fat reference of around 3500 calories per pound.

One pound of dietary fat contains around 3300 to 4222 calories, according to variability of references I have found. If one pound of human fat tissue has 3500 calories then one gram of energy release from stored fat will be about 7.7 calories (3500/ 454 = 7.7). One gram of carbohydrate, stored in the body as glycogen, has a potential of about 4.1 calories. Caloric values in food depict the stored energy potential in food. Caloric values in exercise measure the actual heat produced by muscles as fats and carbohydrates are burned yielding energy. Potential energy not utilized by the body is stored in a long-term storage form, being fat. Extra protein and carbohydrates consumed but not used are converted to fat for storage. Extra fat is already fat and requires minimal changes before being stored.

We need body fat to live, but too much leads to serious health problems like diabetes, stroke, heart disease and can even kill us.

Excess body fat is really excess stored energy and the only way to get rid of the excess is to expend energy beyond what we eat in one day. If you eat 2000 calories in one day, to lose body fat your daily activity must burn off those 2000 calories, plus a little extra. If you eat 2000 calories and expend 2500, some of the extra 500 calories will come from your excess stored body fat. Repeat this daily or on most days and that will translate into pounds of fat loss every month. Don't get too excited about the math being perfect; studies show that genetic differences between people cause slightly different rates of fat loss with the same caloric deficit. That being said, once the right deficit is found every person will lose fat.

The above graph shows average daily fat loss with a 500 calorie per day deficit (2000 calories in 2500 out). We also gain and lose weight daily through hydration/ dehydration, eating, and elimination which can add up to an average fluctuation in weight from morning to night of 2 to 4 pounds. This makes it impossible to practically measure fat loss day to day since daily fat loss is only about 0.2 lb. - You may be losing fat, but in such a small amount each day it doesn't show up on the scale: wait for it though - those small daily losses add up after a week. Don't interpret daily weight fluctuations as and indication to your success or failure in losing fat.

Watch for weekly trends and long term trends over many months. Be careful with interpreting "failure", as we can be our own worst enemy by judging our selves negatively and suffering emotionally as a result. If you don't lose weight, be objective; simply adjust your food intake and physical activity to compensate. This example of a 500 calorie per day deficit is for illustration purposes - each individual needs to find the caloric deficit that produces a result. Typically the deficit required for fat loss is between 300 and 500 calories per day, but could be around 800 calories for some. If you lose more than 2 pounds per week you are likely losing muscle and water as well. Safe fat loss is 1 to 2 pounds per week. Don't get bent out of shape thinking that you have to be perfect every day. While it's true you need consistency for success, losing fat means changing your old habits. Make your mistakes, but get over them. Keep at it and you will succeed.

Fat loss really is this simple, but those selling fads make it sound complicated so they can sell you their special cure.

In order to reduce your fat "reserves", you need to burn off more calories than you take in. Eat less, exercise more.

High Intensity or low intensity exercise; Which burns more fat?

Intensity doesn't really matter if fat loss is the goal; so long as you burn off more calories than you consume you will lose fat. Note that going too hard will cause injury and burn out, and going too easy may not be enough to stimulate change. Start easy, increase as you adapt. Go here to learn about lactate testing and finding the right intensity to exercise. Go here to learn how standard heart rate formulas don't work.

That being said, here is some technical information on fat burning; It takes 75% more oxygen to burn one gram of fat than it does one gram of carbohydrate. This is why it's necessary to be in a very "aerobic" state to burn fat during exercise (we also burn fat during other non-exercise activities, sitting, and sleeping). When unfit there is not enough plumbing (capillary density, arterial diameter, oxidative capacity, mitochondria) to facilitate fat burning during more intensive exercise. When we're aerobically unfit, we tap into our "anaerobic" energy system early to make up for our underdeveloped aerobic systems shortcomings.

This means an unfit person lacks the physical development to burn fat as effectively as a fit person. Unfit persons need to increase fat burning potential through low intensity exercise. As a person becomes more fit they are able to accommodate fat burning at higher intensities via greater ability to deliver oxygen to muscle, and for muscle to use fat as a fuel. A fit person can burn up to 50% more fat at any given aerobic intensity than an unfit person.

High intensity anaerobic exercise for short periods still contributes to calories burned by using carbohydrates. Calories burned in exercise for fat loss can be from fat or carbohydrates or both - it doesn't matter - so long as you burn more calories than you consume. However, for the physically unfit high intensity exercise can promote injury and result in short term gains that are soon limited by plateaus. High intensity exercise is potent, but should be used sparingly and only when properly conditioned to tolerate the high loads associated with intensive exercise. Lower intensity exercise can be tolerated better on a day to day basis so over all there is generally a greater potential to burn more calories with regular moderate exercise sessions rather than less frequent intensive sessions.

So in fact there is no real argument for which is better for burning fat; high or low intensity aerobic exercise. It's both. Low intensity is the preferred method to build the ability to use oxygen, to develop aerobic fitness. Gradually and incrementally, greater intensities can be sustained during exercise. Finally, high intensity aerobic exercise can be done once the base is built, then it is very easy to burn loads of calories while exercising at moderate to high intensities. While this process takes about one year, about a 10 to 20% gain in over all fitness will made within the first 12 to 16 weeks. When a person is ready to exercise hard, no more than 20% of their exercise time should be intensive, unless they are athletic, even then high intensity still makes up the minority of training. While all this is scientifically interesting, it has misled many into believing that to reduce body fat one must exercise in the "fat burning zone". This isn't entirely true..

Fat loss begins immediately when caloric expenditure is greater than caloric consumption. Fat loss can occur without any exercise at all so long as energy from food intake is less than the energy the body uses throughout the day. Recent research has shown The combination of eating less and adding daily exercise does not net a better result in fat loss than diet or exercise alone. Exercise has other health benefits as well, so while exercise may be used for fat loss it also increases the efficiency of the heart, lungs, circulatory system, and a long list of other benefits.

The ratio of consumption to expenditure needed to lose fat is individually determined. If a "clinically perfect" diet and exercise regimen is followed it is expected a person can lose up to 2 pounds of fat in one week. However a 2 pound per week loss is flirting with nutritional disaster as the 1000 calorie per day deficit required may limit vital nutrient intake. More realistic healthy fat loss is about 1 to 2 pounds every couple of weeks, while Expecting transient weight loss with some temporary weight gain, but with a long term downwards trend. Typically those with poor nutrition will be dehydrated. Therefore within the first two weeks of eating more fruits and vegetables as well as drinking more water, a weight gain due to hydration of about 5 to 7 pounds may be expected. This is healthy, it is not fat gain.

Fat Loss: Use the information at the top of this page to estimate your caloric needs. Subtract 10% of the calories from that number. See if you lose fat by measuring your weight and waist girth (both should go down gradually) If not, adjust your mix of food in and exercise out. Dropping below 2000 calories per day is unhealthy for most active males, and below 1500 calories per day may be unhealthy for active females. Cutting by more than 300 - 500 calories below your calculated daily requirement at one time may be too dramatic for many people. Hold your eating/ exercise pattern for a week or two before making changes. You need this much time to make a reasonable assessment.

The Simple Summary for Fat Loss/Gain:

  • We gain fat by eating too much; there is virtually no other way to become overweight.
  • We lose fat by eating less and exercising more.
  • We can not burn off more than 1 or 2 pounds of fat in one week. If your weight drops by more than 2 pounds in one week, you are most likely losing water and muscle as well.
  • The easiest way to implement food changes that will help you lose fat is to reduce your portion sizes of the foods you eat now. Do not be misled by fad diets! Try these actions:
    - Leave a little food on your plate or take smaller servings.
    - Do not go back for seconds.
    - Eat desserts less often.
    - Gradually add more healthy food choices.

Technicalities of which you need to be aware:

Because of a genetic variance between individuals, one person may require less or more of a dietary change, or exercise, than another to achieve a similar result. You can't copy another person's actions exactly and expect the same result. That being said the same principal is applied to each person; find the correct mix of calories in and calories out that produces a measurable result.

Generally there is a better result for fat loss by eating several small meals per day rather than two or three large meals. However, the main determining factor is still the total amount of calories consumed.

Eat less on the days that you have less activity. This is critical.

If you always feel like you have little energy, it may be from not consuming enough food, or not eating frequently enough. It may also be from an Iron deficiency or another deficiency. In the case of any chronic state of constant fatigue, you should consult your physician.

Typically, if you don't feel any lack of energy and then decrease your caloric intake, and then begin feeling like you have less energy (compared to before you decreased your calories), you have decreased your calories too much.

Click here to download free software for finding the caloric and nutrient content of foods. This will take you to a USDA web page with piles of helpful nutrition resources.

Click here for a nutrition calculator. This will take you to the bblex web site (Germany) Estimate the total calories you need in a day. Broken down to grams of carbs, protein, fat, and amounts of vitamins and minerals. Also considers total exercise time.

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