Physical Activity and Controlling Weight

The Key to Weight Control: A simple equation of calories in minus calories out, the old phrase “eat less, move more” is often suggested. This means to simply subtract the calories you’ve expended throughout the day from the ones you took in. But there is a little more to it than just that. The biggest piece of the puzzle is to understand what makes up your Total Energy Expenditure (see below), and how much energy you utilise each day.

Beware of Fad Diets: Don’t let the media or any other source determine how or what you eat. Just try to get enough servings from each of the food groups everyday and control your portion sizes appropriately. Eating frequent, small meals throughout the day will result in an improved Resting or basal metabolic rate (RMR/BMR), which is the amount of energy your body expends at rest.

Total Daily Energy Expenditure

TDEE is the total number of calories that your body expends in 24 hours, including all activities. It can vary widely in populations and is much higher for athletes or extremely active/stressed individuals, as example Chess Grandmasters can use vast amounts of energy despite being classed as sedentary. Caloric requirements may also vary among similarly active individuals due to differences in metabolic status.

Caloric maintenance level refers to the amount of calories you would need to consume in order to maintain your current body weight. There are many different formulas you can use to determine your caloric maintenance level. These formulas take into account the factors of age, sex, height, weight, lean body mass, and activity level. A “quick and easy” method is based only on total body weight and is as follows:

Fat Loss = 12-13 calories per pound of body weight Maintenance = 15-16 calories per #
Weight Gain = 18-19 calories per #

So, if you are a 160-pound male or female wanting to lose weight, you would multiply 160 by 12 or 13. The product tells you that if you consume around 1900-2000 calories per day, then you should lose weight, but clinical experience shows me that individuals with a history of dieting may have greatly inhibited their metabolism causing problems when trying to use formulas, or generic calorie guides.

A much more accurate method for determining TDEE is to determine your resting metabolic rate (RMR) using a metabolic cart that measures respiratory gases to determine a more accurate unique calorie number that is specific to you, then multiply the RMR by an activity factor to calculate TDEE.

RMR is the total number of calories your body requires for normal bodily functions (excluding activity factors). This includes keeping your heart beating, inhaling and exhaling air, digesting food, making new blood cells, maintaining your body temperature, and every other metabolic process in your body. In other words, your BMR is all the energy used for the basic processes of life itself. It may vary dramatically from person to person depending on genetic factors.

RMR is usually at its lowest when you are sleeping, hence we try to test early in the morning, and increases a little every time you eat in order to digest that food. (That is why it is good to eat small, frequent meals.) It also increases if you have a high percent of lean mass, such as muscle. Since muscle is more active than fat. A false metabolic boost by as much as 14% can occur in people suffering the effects of stress hormones (fasting, cold shock, etc) and while many seek to use this as a “bio-hack”, chronic exposure to stress hormones is a risk for numerous diseases, and will ultimately inhibit the metabolic rate.

The Harris-Benedict formula is based on total body weight, height, age, and sex and is therefore more accurate than the “quick and easy” formula used above, if you’re unable to be tested (i.e. you’re too far away from my base in Derby, UK) this would be my second choice. If you are close enough I would always always at least have one test that can determine how far away your result is from what the “norms” may be based on the following formula.

Men: BMR = 66 + (13.7 x wt in kg) + (5 x ht in cm) - (6.8 x age in years)

Women: BMR = 655 + (9.6 x wt in kg) + (1.8 x ht in cm) - (4.7 x age in years)

*note: 1 inch = 2.54 cm and 1 kilogram = 2.2 lbs.

Example: You are a 30 year old female. You are 5'6" tall (167.6 cm) and weigh 120 pounds (54.5 kg). Your BMR = 655 + 523 + 302 - 141 = 1339 calories/day.

Now that you know your BMR, you can calculate your TDEE by multiplying you BMR by your activity level.

Activity Multiplier:

Sedentary = BMR x 1.2 (little or no exercise, desk job)

Lightly active = BMR x 1.375 (light exercise/ sports 1-3 days/week)

Moderately active = BMR x 1.55 (moderate exercise/ sports 6-7 days/week)

Very active = BMR x 1.725 (hard exercise every day, or exercising 2 xs/day)

Extra active = BMR x 1.9 (hard exercise 2 or more times per day, or training for marathon, or triathlon, etc.

Example: Your BMR is 1339 calories per day and your activity level is moderately active (work out 3-4 times per week). Your activity factor is 1.55 and your TDEE is 1.55 x 1339 = 2075 calories per day. This is the total calories you could eat everyday if you wanted to maintain your weight. If you want to lose weight, you would either have to consume fewer calories everyday, increase you activity level, or do both.

Clinically these are not the activity multipliers I use. I use ones that have a greater evidence base, but that is a whole new article, or read about it in my book, Consistent Eating. For this article I have used the commonly known/used activity multipliers.

Of course, the most accurate way to understand your needs is to measure your RMR. Once you have this data, we can determine you TDEE by multiplying your RMR by your activity level(s) and goals.

To book a test, either at my base or in your own home at a time convenient to you, please get in touch. You can find the test in my store, or by clicking here..