Great topic. I started counting calories and lost around 10 pounds. I quickly saw gains in training and started running PRs in training. I was indestructible for a while, doing 3200x2 in 9:25-29. Ran a marathon PR easy. It came at a great cost.
That training cycle wasn't all easy. I would binge at times on foods that I cut out of my diet, then feel demoralized and bloated. My mood would swing all the time. I am pretty sure it accelerated the death of my marriage. The next season I maintained and ran about at the same level. The next season it was a stress fracture. I kept trying to repeat my first season success. My neuroticism increased, I isolated myself because I was obsessed with food. Training became about earning my meals so I could drop more weight which I thought would automatically entitle me to linear gains in performance. Every run was becoming dreadful, but when I thought about food that was motivating enough. The scale became my race course, and I always had to be "on". It was exhausting, and I ended up going from 156 to around 140. I chewed a pack of gum per day and drank a shitload of water. I'll never forget when I was visiting friends at home my old assistant cross country coach made a parting comment about how I was too thin. Everybody heard it but nobody said anything. I was justifying it for performance reasons, so it was ok to do, right?
At times these binges would get so bad I could put down so much junk food I would end up being 10 pounds heavier on the scale the following day with all the water, carbs, and salt. I started trying to throw it up at times, and I remember thinking in that moment as I was sitting on the floor of the bathroom near this nasty toilet how I got to this place. I trudged through my last marathon in my worst performance to date by far. I never set a single PR with the exception of that first marathon. In fact, I was not even close. My Garmin watch said I was in 2:17 shape though, are those things even close to accurate?
I quit running for months, and I ballooned to nearly 180. Eventually my appetite waned and I went down to 160 just eating when I was hungry and deleting Myfitnesspal. No more calorie counting for me. It was liberating. I went through a personally rough season in my life shortly after, without a doubt the worst "season" of my entire life. Thank goodness I did not have to face my disordered eating during this time, but then again I wasn't running so I was coping very poorly.
I started running again after hitting rock bottom, and I try to pay attention to my hunger cues and not deprive myself. I kept to 40-50 miles per week and trained for the shorter stuff. Had my best season to date, but I'll never return to what I was, and that is okay. I had my time in the sun and that time has likely come and gone. What I will say is that the neuroticism of runners combined with losing weight and dieting can be extremely dangerous. You won't realize you are on the crazy ride of disordered eating until you have been riding it for awhile. It is very hard to get off that ride, many never recover.
I encourage you to train smart, hard if you can. Try to be mindful about what you are eating but know that the scale doesn't automatically translate to better performance. It can be very dangerous.