Many people seem to be confused by the interplay of nutrition and exercise in the context of weight maintenance and fat loss. It’s really not that complicated, although it’s critical that you understand how one will affect the other…and how they do that is not unlike, say, driving a car with a manual transmission.

This analogy will be more effective if you already know how to drive a stick-shift, but even if you don’t, bear with me. Imagine you’re in the car: if you hold down the clutch pedal, even if you floor the gas, you’re not going to go anywhere. In essence, the clutch mediates the effect of the gas. Until you begin releasing the clutch, the gears won’t catch and the wheels won’t turn. Now, think of exercise output as being the gas pedal and nutritional intake as the clutch. You can train your butt off, but if you don’t watch your diet, you won’t make progress. That’s not to say that your exercise efforts will be for naught, but if your goal is to shed fat, it ain’t gonna happen. Your food intake will, in effect, mediate the fat-loss effects of your workout.

That’s why it’s commonly said that you can’t out-exercise a poor diet. And that’s why it’s also true that you should never fool yourself into thinking you can eat anything and everything you want just because you workout out on a given day. You can consume far more calories in a sitting than you can easily burn off during a training session, and as a result you’ll end up, pardon the pun, spinning your wheels.

So when someone tells me that they’re working out hard but it’s not making a difference in their fat stores, one of the first things I do is ask then to show me their food log. Don’t have a food log? Well, that’s the place to start. Because unless you’re paying attention to both the intake and output sides of the equation — manipulating both pedals to drive — you’re probably not going to get very far.