Is it okay to run when you're over 300?

Assuming it isn't painful, then you can jog/run at a comfortable pace and distance for as long as you can and walk the remainder. As your weight goes down, and your cardio fitness level increases, you'll be capable of jogging/running for longer duration. Start jogging at a slow pace, initially, to see how that affects your joints. You may experience some level of discomfort, which is alright, but anything that translates to pain is where you'd draw the line and cut back a bit. If you can't run just yet, do not feel disappointed since walking at a fast pace at your weight can burn quite a bit of calories.

Walking doesn't work as quickly, but it's safer and easier to fit in without special clothing or anything. Just walking 30 minutes could give you around a 200-calorie edge each day, I think.

Running can tear up your knees even at 250 pounds, if you don't use good form to avoid bouncing up and down.

When you run you burn more cals, but I am 283 and I run a min, walk a minute and I repeat this for 30 mins. You can do it! Just a light jog will get your heart rate up.

I don't know the research, but I do have some thoughts based on personal experience. I have several family members heavier than you. One tried to run and got serious back and knee problems - with good shoes.

I find that jogging or aerobics in the pool take the pressure off my body because of buoyancy, so they are less stressful.

No one can see my body underwater, which makes me feel better about the world in general.

The resistance from the water adds to the workout. So even if I don't work out that long, I feel the workout. And I work out ALL OVER MY BODY - arms, stomach, back, legs, whatever.

Jogging is great. Walking is also great (and I walk faster than I used to jog). But runners are prone to injuries and heavy runners, I am willing to bet, more prone still.

If you want to run - GO FOR IT. I would think about working up to it with lower impact beginnings. Just my two cents.

Personally I wouldn't do it, you don't want to regret it later if you mess up your joints.
I'd start with walking and swimming

I first decided to try running a few years ago at 320 (something)... I quickly realized I was too big to run. Hurt my back from the impact and that was the end of my running journey.

Recently I've tried running on a treadmill and can go for a minute or so at 4mph but this is extremely hard (at 299 lbs). It hurts my joints and kills my feet/ankles.

I say it would probably be better on your body if you hold off until you are smaller but to each their own. If you want to try go ahead.

I would try walking first, and see a doctor and maybe a PT about developing a weight loss and conditioning plan that will enable you to run over time. You do not want to blow out your knees by running without preparation. I know people who weigh far less than 300 who've done that and it's an awful situation. Forget about exercise, basic mobility is a problem.

Walking is great exercise. Have you tried adding some hills or inclines? That will not only help burn calories but get your heart pumping (which is why you want to jog, right?) Good for you for getting out there!

Why don't you try increasing the speed of your walking or use 2 lb weights when doing it?
Perhaps consider walking 3.8 or 4.0 mph for a full 60 minutes before you begin to run?

There is no specific uniform answer that confroms to everyone, but pain should be the ultimate arbiter. Also, a sore lower back from running is usually indicative of the fact that your core is weak and needs to be strengthened.

Also - if you can get some biking in, I suggest doing that as well.

But at your weight - I would just tell you to take it slow at first. If you do feel pain or soreness, you'll likely feel it the following morning.

Morbid obesity is temporary if you work (through diet and exercise) to eliminate it. However, knee, ankle or hip problems could be permanent and require serious surgery if structural damage is done. Unfortunately, you don't know about that structural damage until AFTER it occurs. Why take the chance? I started at 478 pounds, have been walking religiously in the seven weeks since then. As a result of walking and MFP, I am down 32 pounds to 446. I started barely able to walk 10 minutes, and am now up to 40-45 minutes almost daily even incorporating some steep uphills. Believe me, any extra calorie or strength benefits you seek from running (vs. walking) can be obtained by incorporating hills, ramps or stairs into your walking routine (or even water aerobics, which cause little stress on the lower body weight bearing joints). And doing it that way causes FAR less weight bearing stress on the lower body.