Exercise or Diet: Which Has the Bigger Impact on Weight Loss?

When it comes to weight loss people want to put their effort where it counts. So they ask me..

"Is diet or exercise more important? Is it 50/50? 70/30? 80/20? Should I put my focus on my diet or my exercise? Which one will help me lose weight faster?"

I’m not sure how these ratios between the two factors get determined or even why it became one versus the other. Long story short both are critical to weight loss and health, no surprise I’m sure. If you dive into the research (as I have) you’ll find countless studies supporting both sides of the table in this debate. For as many studies supporting activity, you’ll find just as many studies supporting diet. The media has a field day with this type of research, because it’s relevant and relatable to most readers. After all, nearly 75% of Americans are overweight or obese. This is when you’ll see articles surface titled: “Eating Less is Far More Important Than Exercise.” Most recently, the consensus seems to side with diet being the more important factor when it comes to weight loss. I’ve read the research, have 2 degrees in nutrition, am a registered dietitian, a personal trainer and I’ve worked with hundreds of clients looking to lose weight.

So my thoughts on which is more important…. well, it depends.

I know, probably not what you wanted to hear but that is the truth. I’ve seen some people respond well to increasing activity and then I’ve seen others respond better to changing their diet. After years of reading through research I was interested in applying it to practice. So, I apologize to my earlier clients but in a way they were my guinea pigs (most, if not all were successful in losing weight and keeping it off either way). They allowed me a unique opportunity to learn which individual factors determined whether diet or exercise made the scale go down more. After a while I came to a few key conclusions and knew what to look for. I was soon able to assess a client quickly and personalize a focus (diet or exercise) that would give them the results they were looking for. Now keep in mind, these are my observations over the years, not necessarily peer-reviewed research. But it’s worth taking into consideration.

There is no blanket recommendation, or ratio between diet and exercise, that can be applied to all individuals. It is very personalized. What works for your friend, sister, mom, dad, or child might not work for you.

Both are critical for EVERYONE. I know I just said there are no blanket recommendations that can be made but you cannot eliminate one altogether. For weight loss and health goals, both must be addressed.

The factors that come into play include how much weight needs to be lost, age, current and past activity levels, current and past diet habits, history of weight loss (yo-yo dieter?)

The biggest determining factors are:

1. How healthy is the current diet?

2. How active is the client?

3. How much weight needs to be lost?

For example, if I have a client who has a pretty healthy diet only needing a few tweaks but hasn’t exercised other than walking in a few years, increasing intensity of his/her exercise is going to have a bigger impact. And vice versa. If I have a client who works out 5-6 days a week but eats what they want when they want, I might adjust the exercise a bit but changing their diet is going to end up having a bigger impact. Finally, the amount of weight the client needs to lose comes into play. If you just have the last 5-10 lbs. to lose, pushing fitness intensity and strength is going to help get you down to that goal weight. If you have 15-50 lbs. to lose, the above is going to determine where we start. If your diet is relatively healthy, start with exercise. If you’re very active, start with diet. Finally, if you have more than 50-60 lbs. to lose, diet can usually start you off in the right direction but after a bit of progress you'll also need to focus on both diet and exercise.

Take away: both diet and exercise are important but knowing which has a bigger impact will be determined by a number of other factors. If you have questions or would like to learn more about what specific things you can focus on to reach your goals, feel free to contact me!


Amanda XO


Amanda XO

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