If you’re one of my clients you’ll often hear me say that you can’t out exercise a bad diet. The relationship between diet and exercise tips toward your diet.

One of the oldest, most well-known health proverbs is that you are what you eat. We’ve all see it all over the internet, in newsletters, Facebook posts, on the back of busses, on your toothpaste tube…

It is so common for a reason though, and I see it be true time and time again.

Is it really that simple though?

Is it True You Can’t Out Exercise a Bad Diet?

Okay, that might be a mild exaggeration. But it’s no exaggeration to say your diet has a huge impact on your wellness.

Seriously, no realistic amount of cardiovascular work or strength training will progress you beyond that bowl of ice cream before bed. You’ll be really fit, but as far as getting leaner and more toned, poor eating with a lot of exercise equals slow or stagnant fat loss.

Can You Lose Weight With a Bad Diet, but Exercising Rigorously?

Yes, especially if you just started exercising. However, your progress will slow to a crawl. So while you may technically disprove that you can’t out exercise a poor diet, is it worth it?

Our metabolisms are far more complicated than simplifying it with calories in versus calories out in relation to energy burned. Once you start looking at hormonal changes and macronutrient ratios, things become even more complicated.

For example, as you build lean muscle tissue, your resting metabolism (the number of calories that you burn when in a state of rest) goes up. Although, there’s enough peer-reviewed research stating the increase in metabolic rate is minimal.

What is relevant though, is the improvement in our hormone ratios. Your system is primed for more efficient fat loss. Thus, you start to have more wiggle room in your caloric intake.

So when do you burn the most fat?

Technically, you burn the most fat during sleep. But if you’re consuming a lot of food before bed, regardless of exercise, you’re elevating your insulin levels.

When insulin levels are high, we don’t burn nearly as much fat. You can read a lot more about this topic in my article How to Lose Fat: When Does Your Body Burn the Most Fat?

What about a ketogenic diet?

Ok, so if we minimize our insulin levels to burn more fat, shouldn’t a ketogenic diet work. Yes, but it requires strict adherence to a ketogenic meal plan. This ultimately eliminates the junk food anyway.

You can read more about a ketogenic diet in my article How to Get into Ketosis Fast and Staying There [Safely]

Can you eat poorly if you intermittent fast?

This will help, but it’s not the end-all. In other words, it’s not a green light to eat crap if you’re fasting.

It does undo some of the damage. Especially if you eat within an eight-hour window where your night’s sleep is at the end of the fast. For example, your last meal is 2:30 PM, you go to bed at 9:30 PM and resume eating at 6:30 AM.

This gives you less opportunity to obtain the nutrients needed. So you have to make every meal count within those eight hours.

Want to learn more? Check out my article Intermittent Fasting 101: All You Need to Know [The Definitive Guide]

Diet and Exercise

Two words that are frequently used together. Both are important, but the synergism reached when combining the two is the key.

So yes, exercise helps. But if you’re going to work to acquire great health and fitness, focus on both.

In other words, it’s senseless to undo all of your hard efforts with exercise by eating a pint of ice cream before you go to bed.

In Conclusion on Bad Diet and Exercise

Advanced aspects of metabolism are not the objective of this blog post. All I want you to take away from these paragraphs is to simply be very mindful of your eating habits.

It’s not a matter of, “Well if I eat this junk food, I’ll just go to the gym longer tonight.” It’s important that you realize that diet and exercise are not equal. A simple adjustments in your diet will have a much bigger “return on investment” than 15 extra minutes on the treadmill.

I can’t emphasize that last statement enough!

References on Diet and Exercise

Curioni, C., Lourenço, P. Long-term weight loss after diet and exercise: a systematic review. Int J Obes 29, 1168–1174 (2005).

Jakicic, J. M., Clark, K., Coleman, E., Donnelly, J. E., Foreyt, J., Melanson, E., Volek, J., & Volpe, S. L. (2001). Appropriate intervention strategies for weight loss and prevention of weight regain for adults. Medicine & Science in Sports & Exercise, 33(12), 2145–2156.

Dennis T. Villareal, M.D., Suresh Chode, M.D., et al, Weight Loss, Exercise, or Both and Physical Function in Obese Older Adults, The New England Journal of Medacine, 2011; 364:1218-1229.

Diet and Exercise: You Can’t Out Exercise a Bad Diet

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