There's a contradiction faced by every dieter. The harsher a dieter restricts calories, the slower his or her metabolism becomes. Weight (fat) loss grinds to a crawl. Many of us realize that fasting, or even skipping meals, is perhaps the worst way to specifically strip off fat over time.
Let's start with data including a classic "semi-starvation" study from back in the late 1960s. The results look something like this:
This figure is best read from the bottom-up. Take a minute and soak it up. Drastically cutting your calorie intake isn't pretty, is it? Look how efficient your body can become when it senses starvation. It'll slow its metabolic rate to the point of conserving every gram of surplus baggage you acquired last holiday season. Although this trait was beneficial back in the days of struggling, evolving cave men hoping for their next meal, nowadays it's insidious! Yet something must be done. So how many calories should one restrict on a day-by-day basis?
Good question; it's one that's approachable in many ways.
It's clear from the T-mag Forums that bodybuilders choose vastly different food combining methods including AM carbs and PM fats, all protein plus fat, or all protein plus carbs. But one thing needs to be pointed out: in order to lose body mass – hopefully as fat – one needs to expend more kcal than he consumes. We can't, after all, change the laws of thermodynamics.
Without going into a treatise on the definitions of thermic effect of food (TEF), resting metabolic rate (RMR), thermic effect of activity (TEA), total energy expenditure (TEE), etc. – which can certainly be found elsewhere on T-mag – let's talk about some of the important questions that remain.
First, grasshopper, one must know from whence he's beginning. Without baseline data, how can we assess progress?
There are two ways to estimate energy requirements for body weight maintenance, one more crude but easy to calculate and the other more detailed and presumably more accurate. Let's go with the easier way first. The use of a formula (pick from several dozen) to estimate RMR is commonly used along with an "activity factor." For example, the Harris-Benedict equations provide a number that corresponds to the calories necessary for the basics: cellular functioning and physiologic processes at rest.
These classical equations give us our energy needs. They're fairly accurate, plus or minus 14%, (8) if we lie there like a lump, unfed, in a temperature-controlled room. They don't mean a lot unless that description fits your lifestyle. However, multiply by a single number representing overall daily activity and you have a gross estimate:
That's pretty much it for this method. The resulting number gives you his/ her TEE plus or minus about 20 percent. Yes, that's a lot of potential error, but without a $20,000 metabolic cart sitting in your living room, it'll have to do. The estimate can be tweaked over time as you gain savvy in what it takes for you to make progress. For a ballpark number, consider that most college-age men rate about 3000 kcal/ day of total energy expenditure (TEE).(2)
Individually add in 1. resistance exercise 2. "cardio" 3. thermic effect of food (averaged at 10% of a mixed meal; about 6% for fat, 6% for carbs and 25% for protein) and finally, thermic effect of activity (non-training).
It's easy to consult textbook or internet tables for this latter portion. TEA is simply kcal spent each hour (or minute) during various tasks:
Of course, these "exertion" numbers have resting needs built-in, so caution is called for when adding it all up. The complexity of this method for obtaining calorie expenditure (and therefore maintenance needs) lies in the fact that you're literally breaking down your waking day hour-by-hour. The extra effort should provide a more accurate caloric expenditure for you.
Here's a detailed example of a dieting, hard-training, office working T-man who's performing lots of negatives at the gym and has to clean up around the house a bit. This is for all you obsessive types who love to crunch numbers:
80 kg (176 pound) male; 177.8 cm (5'10") tall; 25 years old:
-plus-
-plus-
(Recall from the calculation that our example is eating just 2900 kcal; this is a very mild 14% negative energy balance.)
Note that last, bodybuilder-specific addition to energy expenditure. An athlete who regularly gets muscular soreness and trains brutally hard most days (be honest with yourself), should also probably add on a "stress factor" of 1.1 to account for the hyper-metabolism of "injury." This is often overlooked when eccentrically-trained athletes compute their energy balance. It shouldn't be underestimated, however; cortisol can raise metabolic rate (4) as can other stressful injury processes. I've seen it and so have others in the lab.(5,9)
After choosing a method and getting one's needs for resting "energy equilibrium," we can then turn our attention to whittling-away a portion of that weight-maintaining energy (calories). Stay tuned for the good, the bad, the restrictive and the contradictive in Part II.
Ask Me Anything I receive great questions in my T Nation Community Coaching Lab. If…
Ask Me Anything I get a lot of great questions in my T Nation Community…
An Exaggerated Warm-Up Isn't Helpful I don't know when the lengthy warm-up became a thing,…
Training and Your Metabolic State When I think "workout," I think of speeds. Your metabolic…