Q&A: Relative Importance of Diet and Exercise for Fat Loss

Question:

Some experts claim fat loss is 80-90% diet and 10-20% exercise, while others say it is 50/50, or even that you can eat anything you want if you are active enough. I know both are important, but where should I put most of my effort if I want to get the best results?

Answer: 

Diet is more important than exercise for fat loss since it has a greater effect on energy balance. You can’t put a percentage on it, though, because the relative proportions of the energy deficit due to restrictions on calorie intake and macronutrient ratios versus increased calorie expenditure from exercise and increases in lean body mass can vary tremendously between individuals. All else being roughly equal the percentage of fat loss due to diet will be much higher for someone who has a lot of fat to lose and is able and willing to restrict calories further than for someone who is only reducing calories slightly. For someone whose average calorie intake is about the same as their average expenditure before exercise the percentage of fat loss due to exercise would be higher (although relying on exercise to create a calorie deficit is very inefficient).

Diet VS Exercise

Diet and exercise (strength training) are equally important if your goal is to improve your body composition and not just lose fat. This is because strength training is necessary to maintain your muscle mass while fat is lost on a hypocaloric diet. If you don’t strength train you will lose muscle, which will negatively affect your body shape and tone and reduce your metabolic rate making it harder to lose fat and keep it off.

If your goal is to improve your body composition as much as possible the relative contribution of diet and exercise doesn’t really matter, though, because you should be putting one hundred percent effort into both of them, as well as all of the other factors that aid in muscle growth and fat loss.

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  • Walt Mar 6, 2017 @ 23:03

    And all the other factors for improved body composition are?

    • Drew Baye Apr 1, 2017 @ 11:45

      Hey Walt,

      There are many, but a few of the most important ones are getting enough quality sleep, hydration, and stress management, which are mentioned elsewhere on the site.

  • Jason Mar 7, 2017 @ 22:21

    Drew,
    I came across your website recently and have been soaking up as much info as possible. The high quality information you write about motivates me to think about making a comeback. I have weight trained for a couple of decades but have taken a layoff for roughly the past year, not because of injury, but loss of passion in training among other things. I am over 400lbs at the moment but I am thinking about getting back into a lifting and diet routine. I like your philosophy of minimal, but really hard training to produce results. I believe getting back into a routine could give me something to look forward to. Thank you for your excellent contributions to the Iron game.
    Jay

    • Drew Baye Apr 1, 2017 @ 11:35

      Hey Jason,

      You’re welcome, and I have no doubt that if you work hard at it you will make a successful comeback.

  • paul crosse Mar 9, 2017 @ 4:49

    As Always good sound advice. Thanks for all the great work you do Drew.
    Paul

  • matt nairn Mar 12, 2017 @ 11:57

    Hi Drew
    Good post. You mentioned before that if an individual aiming to lose fat, you prefer full body workouts performed 2-3 times per week. If I am going to failure on each exercise, I find recovery an issue, so what training split would you recommend? Would a full body workout performed every 4th day be better than a split routine ? Cheers
    Matt

    • Drew Baye Apr 26, 2017 @ 16:55

      Hey Matt,

      If reducing the workout volume doesn’t help, in most cases I would increase the rest time to three days between workouts (a little less than 2x/week) before splitting the workout up.

  • NP Mar 12, 2017 @ 17:53

    It is much easier to cut 300-500 calories than burning 300-500 calories. This is especially true when already in a caloric negative balance cause you will have less energy.

  • Ahmed Mar 15, 2017 @ 6:27

    If only life were that simple!

    This doesn’t work for skinny fat folks. I have worked hard and built muscle/lost fat, but still the skinny fat look doesn’t really go away – my thin arms have become muscular, still the little fat on obliques is there. My chest has become massive, still a little midsection fat is there.

    What u say applies to people who are thin, overweight, or any specific category. Skinny fat is a weird body type, it is like we inherited the worst of both worlds/

    • Drew Baye Mar 28, 2017 @ 16:36

      No, Ahmed, some people just have different fat distribution patterns than others and take longer to lose fat in some areas. The exact same principles apply, however. So-called “skinny fat” people do not have a weird body type, and benefit from applying the same training and dietary principles as everybody else.

  • Guilherme Radel May 16, 2017 @ 20:11

    Hey Drew, sorry for being slightly off-topic here but since the topic is weight loss/cutting …

    It’s common for people to purposely drop some reps and increase weight lifted while cutting with regular workout routines, the premise being it’s better to aim for strength gains/maintenance than to try to build muscle (ex.: a guy from 3×12 OHP to more traditional strength regimes such as 3×5).

    Do people in the HIT world also do this? Ex: if one’s TUL is 60-90s, would the above principle apply? would it be beneficial to do 40-70s on a cut?

    • Drew Baye May 30, 2017 @ 14:14

      Hey Guilherme,

      No, because it is a myth that certain rep ranges are better in general for strength than others. A broad variety of repetition ranges can be effective for improving muscular strength, but some individuals will do better with some ranges than others. For some this might be lower, but others it might be higher.

  • Jon Dec 7, 2017 @ 15:51

    I had an idea recently that’s related to this question, but I have a hard time finding answers to it so I’m wondering what you think Drew:

    Is it possible for the body to burn fat and build muscle at the same time with a very slight caloric deficit if the body gets a proper stimulus to increase its muscle mass?

    For example, let’s assume I’m eating 2500 calories per day, and let’s assume my BMR is slightly higher than that (maybe 2600-2700). I have some fat reserves left, maybe 12-15% body fat. I perform proper HIT with a few days in between, get adequate recovery and I have a balanced diet.

    Now, the strength training to muscular failure signals to my body that it needs to become stronger. However, the body receives 100-200 less per day of “new” calories than it requires to meet its own demands. Is it then possible for the body to tap its storage of calories in the form of body fat to sustain itself AND build the new increments of muscle that it deems necessary to overcompensate for the training stimulus it’s getting?

    I hope I’m making sense here. Love your awesome work on this site Drew!

    • Drew Baye Dec 7, 2017 @ 21:19

      Yes, it is possible to gain muscle while building fat but you do have to be careful not to decrease calories too far. I wrote about this in detail in Getting Ripped.

  • JA Apr 26, 2018 @ 9:06

    Hi Drew.

    If one is reasonably lean (9-11% BF) trying to get to 7%, is there a ratio of metabolic HIT vs longer rest period HIT workouts you’d recommend? Assuming one is conducting 3 HIT workouts per week.

    Metabolic rate is 1550 via indirect calorimeter (13% below average for size, age, etc. – bummer how it down regulates to a degree at leaner levels). Eating 1500 assuming activity multiplier 1.3x.

    Thanks.

    • Drew Baye May 11, 2018 @ 10:03

      No, because it makes little difference to calorie expenditure and fat loss.