I peaked my running mileage at the age of 44 (70 mpw) and set all my PR's at that age. My lowest weight was 128 lbs (I was 5'5"). I continued running, but never much more than 45 mpw and ran my 30th and last marathon at age 55. I switched to triathlons after that. Today I'm 64 and weigh....127 lbs. I hardly run too. Mostly bike and barely break 5,000 miles per year.

I do increase my weight to about 136 lbs during the winter, but rather easily drop the weight as soon as I get serious in training again. I also drink like a fish. Love beer and even wine because my wife prefers wine. If you saw me eat, you'd not think I can weigh so little. Yeah, I probably have a high metabolism, but I like to think it's the high intensity training I prefer rather than the slow slogs.

Two cents.

First cent: see post #2.

Second cent:
A lot of advice here is about reducing carbs. As such that will be true to reduce weight. I am 6 feet 1" and 185 lbs and am sure I would loose weight when I would reduce carbs.
But I'm always fast in the second half of an IM because my body is used to carbs. I take a powergel every 15 minutes. I literally feel the boost every 15 minutes. I heard if you're on a low carb diet the body looses this capability.
That's why I doubt if a low carb diet is suitable for triathletes.

This is very common as our metabolism 'slows down' and our insulin sensitivity decreases as well. I am 53 this year and mainly bike and run. I have to be very careful with carbs now. I am in no ways diabetic. I am 175cm tall and weigh 67kg. My best IM weight was 63 and that was three years ago. I limit my my main carb meal to the evening and take bitter melon to lower my blood glucose after a meal. It is a reality of aging along other issues. So careful with the carbs.

I think it's fundamentally a lifestyle issue. I was 215 (6'1") at 45. I lifted weights. Played Ice Hockey. Drank my beer and wine. Ate what I wanted and worked long hours and then came home and focused on my growing family.

I'm 62 now and weigh 169. I don't have nearly the muscle mass I had before but I do invest 2-3 days/week in weight training so certainly am not scrawny (all at least I don't think so). I train a lot--average about 20-22 hours/week over the course of the whole year. Lot's of SBR but increasingly in long hikes/treks and mountain climbing. I can easily burn through 4,000+ calories on a big hike day with vertical.

I'm pretty sensible in what I eat but I'm not shy about pizza, a burger or steak, or French fries when the mood strikes (just not all the time). I've cut way back on alcohol and have 2-4 month-long cycles/year where I by and large don't drink at all (like before an Ironman).

I have a set of skinny clothes and when they start to get tight I dial back my eating a bit for a while.

I try to eat more early in the day and less later.

Plus I try to take naps, which seems to help as well.

Also, I work less and the kids are grown.

I think it's principally a matter of discipline. Not motivation. My deal with myself is that when my jeans get tight it's time to cut back. It's been a way of life now for 10+ years....

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Randy Christofferson(http://www.rcmioga.blogspot.com

Insert Doubt. Erase Hope. Crush Dreams.

I'm 51. I'm currently running only at 40-45 mpw between 5.5 and 6 hours a week. In the last 12 weeks I've dropped 1 lb per week by controlling my intake, dropping from 162 to 150.

You don't control weight with exercise...it helps, a little. But, only a little...mostly by just creating a little bit of headroom. You control weight by managing your INTAKE to be equal to or less than your expenditure...depending on your goal.

4 years ago, I dropped from 209 to 150. I wasn't training then...I did a little bit of riding to burn a few calories. But, mostly I just walked. I didn't start training until after I was down under 160.

Unfortunately, there is a growing body of evidence that our metabolism is different as we age. Being active (like we are) is one of the best ways to fight it off.

https://www.healthcanal.com/...m+HealthCanal.com%29

https://health.usnews.com/...se-weight-as-you-age