The following chart is taken from various scientific journal articles measuring average resting metabolic rates (RMR) for women.
Finally through experimentation you may find that your true RMR is slightly outside of the ranges indicated here.
As you can see from the RMR charts there is a direct correlation between RMR and your height. Shorter people burn less calories than taller people. In research done by Amanda C et al in 2010 her group directly measured the RMR of 47 women and compared it to the popular RMR estimator equations. The average RMR for this group of women was 1027 calories per day. The average height of the group was 5’5. Interestingly the predictive equations all overestimated RMR, and the worst one overestimated by 700 calories! It’s tough to hear it, but we all just need to eat way less calories than we’ve been led to believe.
In a review of 11 studies done on RMR in over 500 healthy adults (both men and women) researchers found the highest average RMR to be approximately 1800 calories per day (the largest men) and the lowest at 1280 calories per day (Weinsier RL et al. 1992). This research included men and women of varying heights and groups of lean and obese individuals. The only correlation they found to metabolic rate was Fat Free Mass (FFM). FFM is all the parts of your body that are not fat, this includes internal organs, bones, and muscle mass. In other words, your metabolic rate isn’t affected by how much fat you have, it only matters how big or small you are underneath the fat, and that is largely determined by how tall you are.
And if you think the leaner people had higher metabolic rates than the obese people you would be WRONG. In further research done by Ravussin et al in 1982 it was shown clearly that the obese people actually had higher resting metabolic rates than the lean control group. The average metabolic rate of the obese people was measured at approximately 1800 calories per day as compared to 1450 calories per day for the normal weight control group (and the obese group was actually shorter on average than the controls so we would guess based on height that their metabolic rate should have been lower if all other things were equal). The difference in metabolic rate was because the obese people actually had an average of 30lbs more total FFM than the lean people. This doesn’t mean they had 30lbs more muscle, but rather more of everything including organ mass, bone mass, and residual tissue mass (of which a small amount might have been muscle tissue). Out of all these tissues the most active ones that contribute the greatest proportion to your metabolic rate are your internal organs.
Research by Muller et al, in 2011 shows that not only do your internal organs contribute the largest portion to your metabolic rate but that they scale to the height of your body and to the overall size of your body. In other words, the taller you are and the bigger you are the bigger your internal organs are and thus the more calories they burn.
The following is a list of the relative amount of energy each tissue contributes to your daily metabolic rate per pound of each tissue: (data from Bosy-Westphal et al 2009) and yes, the results surprised me too!
• Heart = 200 cals/lbs
• Kidney = 200 cals/lbs
• Brain = 110 cals/lbs
• Liver = 90 cals/lbs
• Muscle = 6 cals/lbs
• Fat = 2 cals/lbs
• Bone = 1 cals/lbs
As you can see from this data, your heart, kidneys, liver and brain are the most highly metabolically active tissues in your body and as you will find out, they actually contribute the most to your metabolic rate. Muscle is actually much closer to fat when it’s at rest. It really doesn’t burn many calories when you’re not working out. Research by Heymsfield et al. in 2001 indicates that approximately 69% of your resting metabolic rate is from your internal organs (specifically the combination of your heart, liver, kidneys, and brain). The other 31% comes from your bones, muscle, and fat tissue. I’m presenting this research to show you that striving to add extra muscle isn’t going to increase your resting metabolic enough to change how many calories you can eat to lose weight. I’m also showing you that your metabolic rate is likely lower than you were lead to believe. These are the cold hard facts about metabolic rate.
As you can see by reviewing the chart most people are likely eating far too many calories in a given day to even maintain their weight let alone lose any. You may also be wondering just how much you’re going to be eating to lose weight. Our virtual nutritionist software will calculate all of that for you based on your measurements including your height, weight, age, waist, shoulders, and the amount of exercise (if at all) you do each day. You will also be given your schedule of strategic ‘eat up’ days to ensure you don’t experience a crash. From here on in you don’t really need to know your metabolic rate per se.
For those of you signing up for my nutrition of PT packages, I will be able to give you the calorie number you need to use for weight loss. I will also give you your maintenance calorie number for your ‘eat up’ days.