The D3 vitamin benefits seem to be important for keeping healthy levels of bone density, absorbs calcium, helps prevent osteoporosis and helps your immune system function at the best. In other words, without the D3, the calcium in your bloodstream will not be absorbed due somewhat to low D3… they need each other. Healthy bone looks like honeycomb when viewed under a microscope. Unhealthy bone is porous bone and the holes and spaces are much larger.
Vitamin D3, part of the D ( actually vitamin D2 that is prescription) vitamin family, is a hormone which is naturally produced right in your body but Vitamin D3 is not readily available in many foods, ( found in fish, cod liver oil and eggs) but your body will actually absorb it directly from the sun. That is where the walking comes in to place. You are not walking just to lose weight. Exercise can make your bones stronger. And I find walking the easiest exercise to do and my wearable weight loss device keeps me on track.
You can receive enough D3 directly from being outside in the sun. Walking, working in the garden, mowing the lawn, just outsie absorbing the warmth and rays of the sun will give you the vitamin D3 you need. The problem is you have to be concerned with skin cancer so cover up when you are out in the sun. Seems like a no win situation. Some people are beginning to lessen the amount of D3 that they are getting. If you absolutely cannot find the time to walk outside, the weather is terrible and the treadmill is right downstairs, well, just take a daily supplement, 200 IU is ok.
Just a few hours every week out in the sunlight with your device with low SPF sunscreen should be enough to allow your body to absorb the D3 it needs.
Again, always check with your physician or other qualified health care provider with any questions you may have regarding a medical condition.