I'm 5'9 and weigh 151lbs (male). Am I too fat to run fast?

No.

Would you be faster at 140? Yes, you would. Should you try to go on a diet to drop down to 140? No, you should not. Should you train harder and up your mileage to get faster? Yes. You should. Will you drop weight if you train harder and up your mileage? Yes. See a pattern here?

Precious Roy wrote:

Would you be faster at 140? Yes, you would. Should you try to go on a diet to drop down to 140? No, you should not. Should you train harder and up your mileage to get faster? Yes. You should. Will you drop weight if you train harder and up your mileage? Yes. See a pattern here?

Not if you eat too much

Build can vary. And it is hard to look in a mirror and judge yourself. My best running weight was 170 lbs at 6'. I tried losing weight, but got slower.

What do you consider fast? I am the same build as you, 33 years old. In college a 4:10 miler and just under 15 for 5k at about the same weight. At 27 I ran 2:31 for the marathon, same weight. Currently I am running around 16:45 for 5k and 4:45 for the mile. Keep training, build muscle.

I ran 16:59 and 4:47 last summer at 157 lbs, 5’9”, 38 yo. I don’t know if that is “fast” by your definition but those times are decent.

Impossible to say.

Different bodies are meant to be different weights.

I ran my beat times at the 3k through 10k in college at 140 pounds being 5’ 8.5”.

As I matured, I added weight even while staying extremely lean - single digit body fat percentages.

In my 40s, I raced 4 marathons with my weight dropping down to 140 for the first one and locking in at 145 for the latter 3. The first one happened to be the slowest but it was my first one and on the toughest course. I’d say the relative performance at each was essentially the same.

Most marathoners my height would likely be 130 or so. I’d break down if I went down to 130.

So, run your mileage, choose healthy foods, eat when hungry, indulge on occasion but not every meal, focus on being lean instead of light, and let your weight be what it is.

I was 5'7, 130 lbs my senior year of high school. Out of the top 5 varsity guys on my xc team, I probably had the highest BMI (was on the lower end of what is considered normal). However, I was the fastest. 4:17 for 1600m, 9:12 for 3200m. 14:55 for 5k on the track. So while your BMI is probably higher than mine as a senior in HS, you don't need to lose that much weight at all if you feel the need to at all. It's all about finding your ideal race weight. Who knows, maybe I would've been a little faster if I lost 5 lbs. But that would've required starving myself, and possibly making me more injury prone. Don't eat less than what is appropriate given your current training, calorie deficits over the long run are not a good idea.

Solinsky was 169 lbs when we was the first non-African to run sub 27.

You will naturally get to your optimal weight if you eat a healthy diet. Everybody has different bone structure, and genetic muscle fibre make-up, so everyone needs a different amount of muscle to propel themselves further. People who have narrow pelvises/shoulders, more of an "ectomorph" type of body, are going to require less muscle to move.

But that's not to say that having more muscle is bad. More muscle is more ability to move. But it comes at a cost. The question is, is the cost/benefit ratio good or not. It doesn't seem to matter if you are 150-160 lbs unless you are doing marathons, because metabolic efficiency becomes so important.

I have no science/evidence to give you an answer, but I’ll share my personal “case study”. I’m 5’10, 155 pounds, and a few years older than you. I’ll race 1500m up to marathon on this weight. I am significantly faster than I was during college when I weighed 140-145. Several years ago I briefly tried to drop a few pounds but that did not feel great. Felt tired and was not recovering well enough. I just let my body dictate weight now as long as I’m living healthy. So no, you don’t need to drop weight if you feel good where you are. Training smarter and more consistently has been much more beneficial for me.

Im somewhere between 170-175 rn and I'm 6'1. I'd say my ideal race weight is 165, but I run 800/1600 and 4x4. I am considered bigger than average for a middle distance guy, but it works for me. I'm decently fast, 4:35, 2:03 and 54.7 from last year, could see myself running sub 4:30 sub 2:00 and sub 53 this year.

5'10 - 152 - 8.8% bmi

Pretty muscular as a I played a lot of team sports before running.

I ran 1:59/4:03/15:41 at this weight.

The lowest I got down to was 145 during XC season, I was probably was a bit quicker then but race weight came naturally, I didn't restrict my diet or anything.

bf%, not bmi ^

It depends on what you consider fast. I think the biggest thing is that you're fit and well trained. It's a spectrum with many factors, weight just being one of them.

I'm 5'9, range between 145-155lbs and have run low 17 5k/ sub 5 mile/ sub 1:20 half/ sub 3 marathon.

Modest times, but with each of those, had I been a few pounds lighter I dont see that making much of a difference. However, had I been better trained... That could have led to a big difference.

Read the book for context on how to actually use these numbers.

You can see 151 on the scale and have that represent differing body compositions, helath, and varying expressions of your running potential.

It's just a number - and not a sure-fire measurement of running ability. Races aren't determined by weigh ins.

You could probably lean out a little further, dropping another 5 pounds or so - but you aren't far off a respectable running weight for your height.

Ramp up training and continue eating right and don't put too much stock in what the scale says.