Calories and Weight Loss

This time of the year many people start to focus on recovering from the holidays and setting resolutions for the new year. Often people would like to lose weight and start making dietary changes. Something we see in our practice, is that patients over-restrict food in some way which can be detrimental to long term health and can impact weight loss. It not uncommon to have to coach patients into eating more and increasing their caloric intake. Patients are often surprised when they start eating adequate calories, they begin to lose weight. To explain this, we need to discuss the basal metabolic rate and what that means for our body’s day to day function.

Everyone has heard the term “calorie”, but do you know what it means? The body burns energy that comes from food; carbohydrates, fat, and protein. The energy created by burning these foods is released as heat. This heat is measured in calories, kilocalories, joules, or kilijoules. When a package of food says a serving size has 200 calories it equates to how much energy or heat will be derived from metabolizing that item. Another way to think about it is that one pound of body fat is equivalent to 3,500 calories of fuel for the body. So how do we figure out how many calories a body needs for daily function, weight loss, or weight gain? We start with the basal metabolic rate.

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BMR

Basal metabolic rate can be measured directly, or indirectly. A direct measurement is taken by measuring the amount of body heat emitted from a person in a room that allows a moderate amount of activity. This process is not a common test to perform, so indirect measurement is frequently used in its place. This is done using a couple of different formulas and is based upon gender, height, weight, and age. These must be taken into consideration since the dietary needs of a growing young person with high activity levels will vary greatly compared to an elderly or sedentary individual. The two common formulas are called the Harris-Benedict and the Mifflin St. Jeor. Most often the latter is used and will be the one we use as an example. See the below formula and conversions provided. Weight is in kilograms, height in centimeters, and age in years. These formulas estimate the calories burned based on an individuals metrics.

• Male: (10xkg) + (6.25xcm) – (5xage) +5 = BMR
• Female: (10xkg) +6.25xcm) – (5xage) – 161 =BMR
• Weight conversion: lbs/2.2 = kg
• Height conversion: inchesx2.54 = cm

For example, a 44 year old male, that is 5’ 10” and that weighs 225lbs.

• 5’10” = 70 inches
• 70x2.54 = 177 cm
• 225lbs/2.2 = 102kg
• (10x102) +(6.25x177)-(5x44) + 5= 1,911 calories as basal metabolic rate

Now that we have the BMR we know what level NOT to go below. This number of calories is what the body burns performing daily functions such as keeping the brain performing, breathing, and digesting food. Dipping below this level, especially long term, may have detrimental effects on health outcomes. Brain and bone development of young people can be diminished and in menstruating women, too low of caloric intake can cause cessation of a cycle, decreased bone density, and infertility. In addition, brain capacity, organ function, and normal cell function can be negatively impacted. The brain needs steady stream of glucose to function so when clients complain that their energy and focus has dropped off after starting dietary changes, the first question should be “are you eating enough?”

Knowing the BMR is the start as now we need to add in the impact of physical activity. Multiplying the BMR by activity factor will result in the number of calories in order to maintain the current weight (see chart below). In standard recommendations, subtracting 500 calories from that number, in theory, should result in the weight loss of one pound per week. However, if an individual is older or sedentary, subtracting that number of calories each day could cause intake to dip below BMR, which should NOT occur. The opposite is considered true for those wanting to gain weight, add an extra 500 calories a day to gain one pound per week. Keep in mind, this is all based on formulas and calculations. Everyone has individual needs that vary based on ethnicity, health status, and genetics. Using this calculation to ensure caloric intake is adequate is then helpful in a clinical setting where weight may be tracked. This has often proven essential in assisting patients in attaining their weight loss goals. Patients may have previously been told to “eat less and move more” or “go on a diet” to lose weight or improve their health. Instead of focusing on these broad recommendations, we focus on measurable data in addition to weight changes.

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Calculation

In our office we can track body fat, nerve function, gut health, sleep, brain function, hormones, blood sugar, and so on. We like to see improvements in range of motion, decreases in pain, improved cognitive function, and increases in the quality of life as well as helping patients reach their weight loss goals.