Question: Is Counting Calories an Effective Tool for Weight Loss?

Answer: Not as much as you might think. (Scroll down for best practices.) 

Yes, of course you have to expend more calories than you take in in order to lose weight (The Law of Thermodynamics - showing off my fancy Duke Engineering degree), but the practical ways of measuring calories are inherently inaccurate. 

There are just too many variables involved.            

For example, running a mile as fast as you can burns far more calories (over the course of the whole day) than walking the exact same distance.

But the treadmill would report the same number of calories burned regardless of your speed.

Also, you have to take into account what's called the Thermic Effect of Food—it takes calories to digest and process food.

Just because the labels may say two foods have the same number of calories doesn't mean you digest both foods with the same efficiency or—even more important—that the two foods have the same effect on your blood sugar levels (which is implicated in how we store fat).

The Thermic Effect of one food may be far less. That would make that food more "fattening" although the label would never indicate this.

When a food label says, for example, "100 calories," all that means is that burning that food in what's called a bomb calorimeter yields 100 calories (actually, 100 kilocalories) of heat.

But wait ...

A bomb calorimeter doesn't have a Thermic Effect of Food, or even a digestive system, or an insulin response, or hormones, etc.

Moreover, trying to measure the exact number of calories you expend would entail that you to live in a hermetically sealed room.

Or that you measure the number of calories, er, let's say, "going down your toilet."

No, thanks.

Simply make most meals on most days "Lean, Green and Marine (i.e., seafood)," stick to the Five Habits* and you never have to count calories.

The Five Habits

• Eat every few hours 
• Eat veggies with every meal
• Eat lean protein with every meal
• Eat healthy fat with every meal
• Save the starchy carbs for after workouts (or throughout your workout day, if that works better for you)