Important Update: Calorie Count will be shutting down on March 15th. Please click here to read the announcement. Data export is available.
Moderators: melkor

Running but not bulking up thighs?

Quote  |  Reply

I'm determined to lose 20-25lbs so I was planning to eat more healthy and do cardio maximum 5 times a week - mainly running on a treadmill.

I would probably run around 2K-5K but I'm just worried about my thighs bulking up. I don't want to lose weight overall but end up making my thighs even fatter because my main reason for weight loss is because I want my thighs to be slimmer. 

So does running bulking up my thighs and if it does is there anything I can do about it?


11 Replies (last)

These are the legs of (imo) the greatest distance runner of all time.


If anything, running slimed my thighs out. I lost 3 inches on each thigh after doing C25K for 3 months. Think my calves lost some inches at first but now they are back to the same dimensions but with MUSCLE!!!! not fat. Honestly, if my thighs started "bulking up" to were they were before, I wouldn't mind because it would be with muscle, not flab.

Running will tone/slim your legs long before it will bulk the muscles.

The only thing that can bulk you up is food. Running, hiking, swimming, weightlifting, and bicycling will not bulk you up.


You can't bulk up on a calorie deficit, or maintenance for that matter, particularly if you're a woman, as we simply don't have high enough levels of testosterone to 'bulk up' like men can. You have to eat more than you expend.

ok thanks for all the replies.

thing is my thighs are fat. they are already muscle cos i did a lot of sport, ballet etc. so i just dont want to keep bulking up but slim it down but sounds like it'll be alright. i just want to lose around 2-3 inches off my thighs really.

thank you again :)

Original Post by solid555:

The only thing that can bulk you up is food. Running, hiking, swimming, weightlifting, and bicycling will not bulk you up.





Dbol without food means you'll just get the hair loss and acne.


Generally speaking it's very hard for women to add much muscle "bulk" even if they TRY to by training with weights. And when you DO want to add bulk, generally it requires a regimen of high weight and low reps.

Running is the opposite of that: It is low weight and high reps, insofar as the muscular activity is concerned. While you may add some muscle mass by running, it will be lean and (as some respondents have mentioned) your thighs will look more toned and sculpted, not "fatter."

You will, of course, need to lose overall fat in order for the fat to disappear from your thighs (or anywhere else). But a balanced program of aerobic activity with sensible food choices and plenty of rest will take care of that. Any lean muscle you add due to increased activity will help you to burn more calories 24/7.

It's win-win!

posts about fear of bulking up always make me think of this article: -policy

i will also throw in the obligatory "have you considered weightlifting?" response. if you're looking to drop body fat (and not just "lose weight" which, without strength work will include an unnecessary amount of lean muscle mass) then it is a must. see the FAQ sticky if you need some ideas.

good luck!

Congratulations on your new regimen of running! You will feel great and it is a good move for your body and mental fitness.

There is a common misconception that women will "bulk up" if they start to run or use their large muscle groups of quads/hams in the legs or strength train. The simple fact of the matter is that women do not bulk up. The women who want to have muscle must work hard through diet (protein-protein-protein) and years of strength training in the right order/weight/reps, etc. There are women who genetically will gain muscle faster than an average women but you would know this about yourself by now.

You mentioned that you do not want your thighs to get larger and that you are already athletic; have you had a body fat test done to see how much lean muscle mass you have in comparison with fat? This is a good first step and will also help you track your progress as you go. Weight is really just a number, knowing the composition of that weight is far more important. Another common misconception is that you can choose where you will lose fat from on your body. You cannot do this. You can work certain muscle groups but fat does not turn into muscle, the two are different and while you gain muscle you can lose fat. You can work you thighs day and night and think this will melt the fat off your thighs but it will not. Your body will use the quickest source of energy as it needs it and eventually the fat will start to come off all over your body. The truth is that most of us have one area that we are not happy with and short of plastic surgery, you may always have a troubled area. You will see overall improvements as you go and keep your diet clean and your cardio where it needs to be along with strength training. As we have learned, we do not bulk up from strength training but we do create a calorie burning body with less fat and more lean muscle mass. Muscle is active and burns calories even when you are at rest, while fat does not.

Typically runners burn through calories and even muscle at times, so your legs should not bulk up. Sprinters on the other hand are using a different type of muscle fiber and intensity and can increase size and most work to do so in order to be faster in a quick amount of time, given the length of most sprinting events.

The bottom line is that you need to take in fewer calories than you burn. If you want to lose weight you need to be in a deficit of calories which simply means that you are taking in less calories than you are burning. You should watch your mix of calories, i.e. how much from protein, fat, carbs, fiber, etc. You can find a healthy balance of what is right for your dietary needs on this web site and many others. Track your calories carefully, the biggest issue is people underestimating what they actually eat in a day and how many calories those foods have.

The same can also be said of the calorie burn information on gym equipment, it overestimates what you burn. There are devices that are more reliable but still have a margin for error such as the bodybugg.

Ultimately, if you watch what you eat and make wise food choices and make sure you are eating and not starving your body of the nutrients it needs to provide you with energy and you are exercising... you are doing a good thing. How serious you choose to become about your progress is a decision you will have to make. Anyone can become super fit but it does take work, committment and willpower as well as proper planning and it is not always comfortable, even though the payoff of what your body is capable of is so worth it in my opinion.

11 Replies