Dropping weight before an uphill run?

I'm taking part in a short but steep uphill run. It's only 910 meter, but it goes up 314 meter. The course record is 7:58, while the average exerciser (male) is probably around 14:00-15:00. Last years results (male only):

``````#       Time:
1       08:00
10      08:54
100     10:33
500     12:12
1000    13:15
2000    15:18
2500    16:43
3000    19:28
3300    34:00
``````

I've always finished somewhere between 11:00 and 12:00. This year I'm in worse shape than ever, so I'm hoping I can cut some seconds by reducing my weight. I'm wondering though, will I gain a lot by dropping 1,2,3.. kilos prior to the race, or will the loss of muscles prevent me from performing better?

I'm 187 cm, 86 kg.

For the record: I don't really want to lose weight in general, but I'm willing to do so temporarily in order to get a good time. I don't have the time to exercise any more than I do now, so the way to lose weight for me is simply by consuming fewer calories.

Any other tips are of course well-received!

Pure physics (if it was straight up)

If this was a pure climb (straight up), and assuming a race time of 12:00, and body weight of 86 kg, this would require an average of 410 W. Assuming I'm still able to output the same power after a weight-loss, then the finishing time will just be `12:00` scaled by a factor of `New weight / 86 kg`. So, if I go down to 83 kg, I'll be able to finish in about 11:34.

But, this isn't a straight up climb...

• To clear up a misconception: The weight you will lose will be mostly fat. Catabolism of muscles wont significantly happen if you drop 3 kilos at that weight/height.
– John
Aug 25, 2016 at 12:50
• Well, isn't that a good thing! :) But really, if I simply eat less a few weeks then I won't lose muscles? So no downsides (except less chocolate of course)? Aug 25, 2016 at 12:54
• Pretty much, yes. 'Starvation Mode' has been thoroughly debunked on other questions.
– John
Aug 25, 2016 at 13:42