How to Estimate Maintenance Caloric Intake – Q&A

Question: If you would allow me a brief intro . . . my name is Leland Hammonds and I am a 29 year old Kinesiology professor here in San Antonio, Texas. I also own my own personal training business. For the last three years, I have spent approx three hours a day, six days a week studying nutrition and exercise research as they relate to fat loss. It consumes my every waking thought.

Although I do absolutely no marketing – I am booked solid Mon-Fri early mornings and late evenings (basically every second I am not at the college) with fat-loss clients. I believe this has more to do with my client selection/admission process and absolutely constant nagging about nutrition (I normally do not allow a client to continue training with me if they don’t get their nutrition right within the first few weeks of training). All my clients are referrals and almost all of them want fat loss.

That being said, although I read research incessantly, I was very apprehensive about using the internet and hearing what the “fitness experts” are saying and advocating. While I still believe a strong filter should be in place, I am so glad I changed my mind. Your articles, interviews, and books and been such a help to me, I felt obligated to thank you via email (I have also enjoyed Alan Aragon, Alwyn Cosgrove, and a few others but your work has really inspired me – end of dorky praise).

I have a few questions for you (sorry I am not using the forum – but basically they piss me off and I am always dumber for reading the crap in them), I know you are busy so I will just ask one (for now). First, I have read tons of your articles on the internet (I think I even found something you may have doodled on a napkin and threw away and somehow it made it to a website!) and I have only found that you mentioned multiplying a woman’s bodyweight for 14 and a man’s by 15 to calculate maintenance calories.

Because your a true nerd like me, I don’t believe that what you would actually do with a client (figured you mentioned it for simplicity and not to blow your readers minds) and was wondering if you would share what equation, formula, or what have you that you to set maintenance calories, taking age, weights, height, and current activity level into consideration.

Answer: Actually that’s exactly what I do and I’m going to explain not only where those values come from but why I do it this way. Assuming average activity (1 hour of exercise + normal daily activity), 14-16 cal/lb is usually a decent enough starting point for maintenance. I ignore all of the other variables since they don’t usually add much except complexity to the equations. Yes, they do affect things to be sure but, unless you’re looking at real extremes of age, body fat, height, etc. I don’t find that they add much overall.

You can prove this to yourself by comparing values spat out by the more complex equations compared to the quick estimates for a variety of different numbers. The variance usually isn’t much more than a couple hundred calories either way and you have to adjust for the real world anyhow so I just use the quick estimates and go. I have better things to do with my day than work math. I’d note that if you had a client that was at the extreme end (e.g. 80 year old woman), it might be worth working some of the more complicated equations to get a more accurate starting point.

But for the clientel most will end up working with (in a certain range of age, body fatness, etc), the below will be close enough to start. Anyhow, I base the 14-16 cal/lb on the following values which takes into account the four major variables that determine daily energy expenditure.

Resting metabolic rate: 10-11 cal/lb. Women use 10, men use 11. If you work something like the Harris-Benedict equation (which includes age, weight, etc.) for most realistic ranges, it’s always within shooting distance of this value. So I use the quick estimate. For example, I plugged my numbers (37 year old male, 5’7″, 155 lbs) into one of the online calculators and it spit out 1630 calories for RMR. 155*11 = 1705 calories.

Thermic effect of activity: This is always a crapshoot since it can range from a mere 10-20% over basal (if you sit all day) to 100% of basal if you’re involved in heavy activity. Assuming relatively average daily activity and training levels, a 30-50% multiplier is usually sufficient here. So 10-11 cal/lb becomes in the realm of 13-15 cal/lb. This assumes and includes an hour of exercise per day or so.

Thermic effect of food: Although it can vary slightly (especially if you look at extremes of diet), TEF usually amounts to about 10% of the total food intake. So add another 10% to the above. So 13-15 cal/lb becomes 14-16 cal/lb or so.

Non-exercise activity thermogenesis: Of course there’s the additional component of NEAT which can vary massively between individuals. This can’t be readily estimated so I leave it out. It also only appears to be particularly relevant during conditions of overfeeding so I’m not sure it matters much for dieting applications in the first place.

Note: if you want a more detailed look at each of the above variables, I did a rather long article about Metabolic Rate that goes into this in more detail.

In general, women or those with a ‘slower’ metabolic rate should use the lower value (14 cal/lb) and men or those with a ‘faster’ metabolic rate should use the higher value (16 cal/lb) as a STARTING POINT ESTIMATION for maintenance calories.

By the way, slower and faster above are sort of subjective decisions, usually based on previous dieting and relatively tendency to gain or lose weight. It simply represents inherent variability in the components of total energy expenditure.

Ok, I put those last three words in caps to make a point, no matter what equation you use to ESTIMATE maintenance calories, that’s all it is: an ESTIMATION. Basal metabolic rate can vary somewhat even for people with identical stats, differences in activity add up, TEF can vary a bit and NEAT is the big wild card. People tend to use the equations as holy writ when all they are are estimations.

Now, from that estimated maintenance value, say someone wants to lose fat. A reasonable reduction for a moderate deficit diet might be 20% below maintenance which is 3 cal/lb (e.g. 15 cal/lb * 0.2 = 3 cal/lb). So ~14-6 cal/lb becomes ~11-13 cal/lb. Bodybuilders have long used 10-12 cal/lb as a starting point for fat loss; turns out they weren’t all idiots after all. For mass gains, you’d add to this estimated maintenance of course but your question wasn’t about muscle gain so I won’t talk much more about that. Clearly if you used a different deficit or surplus, you’d get slightly different values.

Now, here’s the key thing that most miss: the above ESTIMATES have to be modified based on real-world body composition changes. Because it doesn’t matter in the big scheme of things what some ESTIMATE EQUATION says should be happening if that’s not what’s happening. So then you have to decide what you consider a reasonable rate of either fat loss.

On average a male may be able to achieve 1-1.5 lbs true fat loss per week on a moderate deficit diet although this will be somewhat lower if he’s very lean and somewhat higher if he’s very fat. That’s assuming no muscle or performance loss mind you. Females, by dint of their smaller size usually have to accept lower rates of fat loss without truly heroic efforts. Two pounds per month true fat loss may be all that’s realistically achievable. Sucks, huh?

So any estimates of caloric intake have to then be adjusted based on whether or not that true fat loss is being seen. Losing less than that, you may need to reduce calories slightly. Losing more or losing performance, calories may need to come up. I’d note that this is a topic I address in more detail in both The Rapid Fat Loss Handbook and A Guide to Flexible Dieting, in both I give the scheme I use to adjust calories while dieting based on what’s actually happening in the real world.

I’d note that it’s not quite this simple, water retention can mask true fat loss and fat loss isn’t always linear (there are often stalls and drops that occur, a topic I’m currently looking into in some detail right now). A female who is only losing 2 pounds per month, but who retains 5 lbs of water during her cycle may think that the diet is not working when she’s actually on the perfect caloric intake.

But if someone is extremely inactive, I’ve seen them needing 8 cal/lb to lose fat effectively even if they exercise daily. This is more common than you think. Sitting at a computer all days burns crap all calories, even standing up every few minutes significantly increases this (we’ve been using the Bodybugg to track it). Add an hour of exercise per day at moderate intensities and you don’t get much. Calories have to come down (or activity has to be consciously increased in either volume or intensity) for effective fat loss.

People who are insanely active may have to go much higher calorically to avoid excessive deficits and/or performance drops. This is the exception of course and probably not a major part of your clientele. Folks who are doing 4+ hours/day of training don’t usually hire personal trainers for fat loss.

But these tend to be the exception more than the rule so 14-16 cal/lb for maintenance and 10-12 cal/lb for fat loss work as simple and effective starting points. Since they have to be adjsuted based on real-world changes anyhow, I don’t find that using more complicated equations adds very much unless you’re just trying to impress your clients with your math abilities.

Put a bit more simply: since any estimate you’re going to use will have to be modified by real world changes, and since the more complicated equations invariably give results that are at least within close shooting distance of the quick estimates, I simply choose to use the quick estimates (which I’m going to have to adjust anyway) and spend my time doing more valuable things.