Trainer on the Run Q &A
February 18, 2010 by Sarah
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Thank you for the kind reception from all of the Mom on the Run viewers. We received one question but it was a really great question.
QUESTION:
I am told having a deficit in the number of calories I consume daily (in addition to exercise) will allow me to lose weight. In your opinion, what is a safe deficit? For instance there are days when im 100 or 200 cals under, is it safe?
ANSWER:
Excellent question! First, I want to point out that you are on the right track: diet and exercise go hand in hand and to really be successful in getting healthy you need to consider both. Most people, believe it or not, do not realize that but it’s very important!
OK so now that we have it confirmed that diet + exercise = success back to your question. How much is a safe calorie deficit? To answer this let’s learn two cool trainer abbreviations: BMR and RMR.
BMR=Basal Metabolic Rate
This is a fancy phrase used to describe the minimum amount of energy (which we tend to think of as measured in calories) needed to keep your body running normally. Keeping our body running normally is definitely a good thing!
RMR=Resting Metabolic Rate
Where BMR deals with the true basics of body processes: ventilation, blood circulation, and temperature regulation, RMR refers to the amount of energy you need to carry on a very minimal existence beyond this. For example an RMR might maintain someone who wakes up, works two feet from their bed, and goes back to sleep. Without a doubt most people need at least slightly more than the number of calories their RMR would suggest. Your RMR is only about 10% more than your BMR.
Now that we have that background let’s get back to answering your question:
The quick and easy answer is to never go below your resting metabolic rate (RMR). Makes sense, right? But what would this number be? For women it’s around 1200 calories and for men around 1500 calories (like we needed another example of why it’s much easier to be a guy, right?). Now I say this is the “quick and easy” answer because eating 1200 calories might be “safe” but it probably isn’t all that healthy or the best way to lose weight. This is a more personal matter. First, you will want to figure out your average daily activity and calorie intake when you aren’t thinking about creating a deficit. From here your 100-200 calories under that “normal number” would be PERFECT! I would say the maximum calorie deficit you would be able to maintain without feeling super deprived would be 250 calories.
To sum:
A safe and reasonable calorie deficit = 250 cal/day or less
NEVER below 1200 cal/day for women or 1500 cal/day for men
DIET+EXERCISE=HEALTHY long term weight loss
Fun “Fact”: With a constant food intake (# of calories/day is always the same) and an exercise program completed 3 times per week with an intensity and duration of 300-400 calories a session could equal a 16-pound weight loss in one year!
In more realistic terms: If you weigh 150 pounds and set your treadmill at 5.2 mph (11.5 min/mile) -a slow jog- you would burn slightly over 300 calories in a 30 minute session-not bad right?
Does this help our other bloggers? Let me know any of any lingering concerns or questions you might have on this issue and keep the questions coming!
-Trainer on the Run
What an informative post-thanks for that!
Thanks for this – lots of great information! I’m wondering if you might be able to discuss the best way to determine how many calories you’re burning through exercise. I know using a heart rate monitor is the most accurate, but do you have any other suggestions?
.-= Katie @ Health for the Whole Self´s last blog ..Write Your Healthy Living Memoir =-.
This is a fabulous post! very informative =)
.-= Mari´s last blog ..A Day of Shopping… =-.
Fantastic post! As with everything I think that moderation is key…especially with calorie deficits. Slow weight loss will stay off longer than fast weight loss, mainly because the methods you use to get there are usually lifestyle changes rather than quick fixes.
.-= Joanne´s last blog ..Snickerdoodles! =-.
I love weight loss math – this is very helpful – thanks!
great info!
.-= Simply Life´s last blog ..Fiber One GIVEAWAY! =-.
thanks for saying hi on my bloggie yesterday, TGIF And hope you have a great weekend!
.-= Averie (LoveVeggiesAndYoga)´s last blog ..Raw Vegan Coconut Oil Chocolate, Mailbox Goodies =-.
Great Q & A sesh!
Thanks ladies for your wonderful comments!
Katie-
While using your heart rate is the preferred and more accurate way to determine how many calories you burn during exercise, there is another way to get an estimate using an equation based on MET levels.
You might have noticed the abbreviation MET on some cardio machines (most recently I’ve noticed that Cybex equipment seems to show these values pretty regularly). MET (Metabolic Equivalent) values rate activities based on their intensity. One MET is defined as 1 kcal/kg/hour and is roughly equivalent to the energy cost of sitting quietly. For a comprehensive list of MET values for various activities check out the PDF on this website: http://prevention.sph.sc.edu/tools/compendium.htm
Once you know the MET value of a particular activity you would calculate the number of calories (kcal to be most scientific) required to complete the activity for one minute using the following equation:
(METs x 3.5 x body weight in kg*) = kcal/min
——————————–
200
*to determine your weight in kg divide your weight in lbs by 2.2
This equation is used to determine calories burned on your favorite exercise machine (it’s why your treadmill asks you how much you weigh) and on online websites that estimate the number of calories you burn per minute for various activities.
MET values are quite useful in comparing your cardio workout on one machine to your cardio workout on another machine. However, using the above equation is never going to be as personally accurate as using your heart rate. This is because depending on your personal fitness level you will use more or less oxygen to complete an activity. The amount of oxygen you use directly relates to the amount of calories you burn.
So…heart rate is key! BUT when we use this value to determine calories burned we are likely using an estimate of our maximal heart rate and not a value determined from a lab so even heart rate values won’t always get us to the most precise value of calories burned.
BOTTOM LINE:
*METs (metabolic equivalents) are used to calculate calories burned for an average individual for a given activity. METs can also help you compare the intensity of one machine to another (most useful purpose of METs.
*Equations that use your heart rate to determine the energy cost of a particular activity are much more accurate because they take your personal fitness level into account.
*Even though using your heart rate to calculate calories burned isn’t 100% accurate, paying attention to heart rate is extremely important and useful for cardiovascular training.