Thanks for helping out! It seems that all pics get downsized a lot regardless of the original file size and the uploading method. The main thing is to take relatively sharp photos in decent lighting conditions - preferably with light coming from above and/or from both sides.
In fact one sided lighting is very good for food photos. Its what I do and is recommended by professional food photographers when using natural light. Light needs to be behind or from the side. Overhead is OK but produces flat results. See my set up photo here with back light. Resulting photo is the post after. Its shot on mobile phone. No tripod. No extra lighting.
The downsizing on CookingBites really doesn't affect the images too much so long as your original images are high spec as you say. I can see the difference if I compare my images on my computer with the same images on CookingBites, but its not too bad.
We still don't know why you can't attach images over 2.5MB and yet TastyReuben and I can...