To all those runners out there, I’ve been on the keto diet almost nine weeks now, my energy levels have certainly improved running wise, I can now go for long runs at slower intensities without bonking; however, after running, my legs ache for the rest of the day. I also really struggle uphill. I eat around 45g of carbs each day now. I’d rather not carb load before running or do targeted keto but I know a lot of people say you need carbs to run fast. Even when I don’t run, despite taking electrolytes (enough potassium/magnesium/sodium from food plus added salt daily) and drinking plenty of water, my joints are stiff all the time. I eat around 2500 calories max a day (I only weigh 8 stone so I dont want to lose weight). I run about 15/20 miles a week and do weight/strength sessions twice a week. Will the heavy legs eventually subside? Will I be able to run uphills well? Will the joint pain disappear. For the record, I’ve never had joint pain at all before doing keto. Any advice would be gratefully received. Many thanks 
Running on keto - 9 weeks in
They should subside, but I don’t think anyone knows how long that takes. This is a study comparing keto/low carb versus high carb runners:
They both had similar glycogen response, but the keto runners were keto for 20+ months.
I’d concentrate on salt and even increase it, particularly if you’re getting any muscle spasms.
There’s nothing wrong with 45g carbs/day if that helps. Not everyone needs to be <20g/day. Back when I was on Twitter, I followed a guy who ate 80g/day and was convinced that >80 = weight gain, < 80 = weight loss, independent of calories.
For the joint pain/stiffness, I’m not sure about that. I can’t see what about keto would cause that, and in fact, with many/most, it’s the opposite: keto reduces joint pain. But that might be an effect of reducing “inflammation”.
Maybe its a temporary increase in uric acid?
https://abcacupuncture1.com/does-joint-discomfort-result-from-dumping-oxalate.html
“Gout is caused by uric acid crystals in the joints and can be managed through medications, diet changes, and lifestyle modifications. Gout attacks occur when uric acid levels are too high, leading to inflammation and pain in the joints.”
See also: " A 2012 study found that people experience an increased risk of gout when they first enter into ketosis due to an increase in uric acid levels. However, the risk is short-term and improves once your body adapts to being in ketosis."
Thanks Bob. Just been looking at the ‘foods to avoid and limit’ list for gout. I have a tin of sardines nearly every day and eat a lot of spinach daily, avocado, mushrooms, salmon and tuna. Will cut back on some of this. Thank you for all your help and advice 
It takes 6-12 weeks for fat adaptation. But… it is not like a switch gets turned on and you are suddenly fat adapted. Your muscles will slowly feel less and less lead-like over time. If I recall correctly, it can take up to six months for athletes to become fully fat adapted, but I don’t remember where I saw that.
This article may be of interest:
Yes, I have read that, too. I am never weak or fatigued, it’s just the constipation and salt I need to get to grips with. Thanks Edith.