First, some words on my fitness history:

I was quite a scrawny kid growing up but in high school I joined the high school's Cross-Country team and started running regularly for part of the year. I found that each year as the season started and I worked on getting back into competition shape I would gain about 10 lbs. and my legs (specifically my thighs) would increase in size. I thought this was unusual, since distance running is usually associated with toning muscle rather than building it, but building muscle is what happened. This may be in part due to the fact that I lived in a mountainous part of the country where some of my training runs would often have elevation gains of one hundred to several hundred feet. We would also incorporate hills into our speed workouts. Particularly for me, I enjoyed running hills and so would seek them out on my own personal runs. This may have contributed to the increase in muscle size. I also lived in a higher-altitude environment (about 4500 - 5000 feet) so the air was thinner. To be more specific: 2005 started Cross-Country, ran summer and fall 2006, spring, tried out lacrosse for a season, wasn't very good. 2006, summer and fall, Cross-Country again 2007, spring, track (1600 m and 3200 m) 2007, summer and fall, Cross-Country again (I sprained my ankle shortly before the season started so I was out of commission for a little while). 2008, spring, track again (1600 m and 3200 m).

I then ran a little bit in spring of 2009 recreationally.

Summer 2009- summer 2011 spent two years in a humid sea-level environment where I did a lot of walking but little running.

I didn't start running again until summer 2013, but didn't get to run very long or very often because I was dealing with shin splints. There was nowhere flat where I lived so every run consisted of at least a 40 foot elevation change.

However, from spring 2012 to spring 2014 I started biking regularly to school, which I lived about a mile away from and had a significant downhill one way and a significant hill the other way.

I believe my thighs and buttox are disproportionately bigger than the rest of my body. For instance, I have to buy relaxed fit jeans that are at least 2 inches too big for my hip size just to fit my butt and thighs comfortably into them. For instance, my thighs measure 27 inches EACH while my hip measures at 36 inches and my waist measures at 35 inches. I do have some stomach fat, but since my legs increase in size while I was in good physical condition and had almost no fat on my body I am sure that most of my leg size is coming from muscle.

Most of this leg volume was developed running Cross-Country in high school but I believe some more leg volume has been developed in my exercises since and possibly even gained some fat since the beginning of 2012 (that's when my face and body started looking less scrawny and I started getting some stomach fat).

I have been afraid to take up any sort of exercise again in fear that it would again increase my leg size and I would need to buy pants way larger that my waist/hip size just to get my upper leg to fit.

First question: how did my legs get so big? Was it any particular exercise I did or am I just a genetic anomaly?

Second question: I now live in a flatter part of the country but I still am planning on biking to school most every day and there is a little bit of a hill. How should I approach this biking to keep my leg muscle size from increasing?

Third question: What kind of exercise can I do with my bike that will allow me to burn fat and build strength/endurance without increasing my leg muscle size?

Fourth question: What kind of exercise can I do IN GENERAL that will allow me to burn fat and build strength/endurance without increasing my leg muscle size?

I am a 24 year old male. I would also prefer exercises that don't take a lot of time (whether in preparation or implementation) since I am in a busy stage of life (aren't we all :)? ).


5 Answers 5


While you could blame genetics, biking up enough hills and eating enough food will get you big legs. Nothing to be done about that. So don't do that.

If you want less leg muscles, you need to burn them. You want to train longer at a lower intensity. You also want to consume less protein so that your body can't build new muscles and ultimately can't maintain the ones you already have. (But don't overdo it, you need some protein to survive)

Cardio is a good way to loose muscle in general. heropup mentioned correctly that cyclists look how you don't want to look. I don't believe that they got their muscles just from biking though. They probably spent a lot of time in the gym pumping heavy weights, with small reps. So you might do better walking up the hills, or at least choosing a very low gear to avoid pumping your legs. Also don't do sprints.

But yeah, as has been said already, I also believe that nutrition is MORE important than exercise. If you eat lots of carbs like RyanO suggested, you might just burn the carbs and not your muscles. If you want to burn muscle, you need to be in a fasted state during your workout. I suggest cardio in the morning before breakfast or fasting during the day, followed by cardio in the evening. Look up "intermittent fasting" if you want to know more.

A limited protein and carb intake leaves fat as the main macro nutrient you should be consuming. And if various sources are to be believed (mainly paleo proponents) then you don't even need to watch the calories. The theory goes such that by consuming lots of fat, you teach your body to burn fat to get the energy it needs. As perplexing as it sounds, you won't get fat even if you eat a lot of fat. Also, if you'd consume less calories than what you need, you'd run the risk of developing some pretty nasty eating habits. You want to lose muscles, not binge and get fat.

I suggest trying a low-carb, moderate protein, high fat diet, with a carb re-feed day once a week.

Please be aware that it is dangerous to lose muscle like that. Muscles protect your joints and bones. Risk of injury is high during long cardio sessions, especially when you're running on empty. You might want to ease into it.

Here are two links for further reading:



The 2nd link is about losing fat and gaining muscle, but offers some interesting ideas on nutrition and exercise in general.

Good luck man, I feel your pain. I too am not pleased with my exorbitant leg muscles and started to follow the exact advice I've given you here. Too early for me to confirm or deny the success of this approach yet, but I'll try and check back in in a couple weeks.


From what you've said I'm assuming the volume in your legs is largely muscle, but also with thighs the size of an olympic cyclists, presumably a somewhat significant level of fat. Achieving this size due purely to muscle is very difficult. (This is however a big assumption, so please correct me if I'm wrong.) The 10lbs gained during training is likely due in part to water retention, some muscle growth and an increase in fat from eating to compensate for the training.

Fat can be reduced through diet like the previous answers have said. Begin by tracking the amount of calories you currently consume, tracking macros (fat, protein and carbs in your diet) can also be useful, then reduce your calories by ~300-500kcal and redistribute your macros. A good balance is around 50% Carbs, 30% Fat and 20% Protein, though it depends on your activities. e.g. Endurance exercise might need more carbs, strength training requires more protein for muscle growth etc.

While counting calories can be useful, and many people swear by it, it is also important to eat the correct things, varied fruit and vegetables, complex carbs, fesh meat (or other natural protein sources if youre vegetarian etc.).

Unforunately there are still many uncertainties regarding diet and weight loss, but its a case of trying different approaches until you find one that suits yourself.

Regarding muscle size, unforunately if you wish to continue improving strength/endurance, you will gain muscle. It isn't likely to increase drastically/rapidly since you sound like youre already fairly well developed.

And like heropup said, if its an aesthetic thing, begin training your upper body to improve proportionality. From what I understand though, it wont reduce the rate of muscle growth in your legs (unless of course it takes time away from training your legs.)


I didn't see it mentioned, but diet is very important.

The saying "Abs are made in the kitchen, not the gym." applies here too, if you eat less calories than calories burned, you won't gain unwanted weight!


Have you seen cyclists? They generally have legs that are much larger than their upper bodies, especially those that do time trials. So, I don't recommend cycling if your goal is to prevent thicker legs.

What's going on here is almost entirely genetic and won't be significantly affected by controlling diet. My advice is to focus on upper body compound exercises, such as chest presses, rows, and core workouts. This at least will help balance your proportions, and it may possibly help divert your body's tendency to build muscle in the legs.

With diet and cardio, you can burn fat and get more lean, but it is my opinion that this isn't going to do a whole lot for your leg size, and it definitely will not correct the proportional appearance, unless your exercise focuses on upper body development.


I am sure the size of your legs is a combination of genetics and hypertrophy from the exercise you have participated in.

I agree with the taking in less calories. You will lose weight, but there is no guarantee where the weight will come off. I would working getting leaner overall through exercise and diet, but at the same time learn to accept your legs as they are. Easier said than done I know.

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