diet for lightness and speed?

Question
Kenneth
I am 56, and after many years off with health and weight problems, I plan on getting back into walking, jogging, then running, and eventually swimming. As a skinny lad I was quite a fish, then I turned into a whale! I am also a former soccer coach with an interest in all sports and physical training, especially those sports requiring 'speed', and lightness. For those types of  atheletes, especially those that need to drop the pounds, what is the current diet advice?
For the general public, low carb still seems to be in. I have tried it without much success. Low energy, indigestion, etc. I have gone back to the old low fat diet, and I am starting to see results. All the fastest swimmers and runners I ever knew shunned fat, except for a bit of 'good' fat, and loaded up on carbs and fruits and vegetables. It was the boxers and wrestlers that needed less speed but more brawn, that ate more meat to build up muscle. I find that as long as you count grams of fat, you can eat a ton of carbs and have a ton of energy. Thanks for your thoughts!

Answer
Hi Bud:  As you can understand, my expertise is not in the area of health foods and proper diets for different  genres (sports & related skills). However, based on your own PAST HISTORY of sport involvements, I think all that is needed here is some common sense and review of what diets as a younger man and sports person appealed to you. In other words: 'go with the flow.'
Utilize the diet(s) and food that made/make you happy. Of course, this involves limited use of white starches and sugars. Limited use of soda (fructose, etc.) and watered-down sweet drinks. Make sure you get an adequate diet Vit. B complex, C,D, etc., etc. Also, In training include   at least 20 minutes+ of daily cardio-vascular exercises. My personal [added] advice.  Drink water only when thirsty!! When I was younger & training for marathons and especially in sports that required running and movements for extended periods, I did not carry around bottle(s) of water. I drank water before the event or after and that "only if thirsty." Drinking water when the body doesn't ask for 'agua' puts an addition burden on the heart and circulatory system. Lastly, daily training and cardio-vascular "work" requires a good night's sleep.  That's when the body & YOUR mind recup and produce mental, physical & neurological growth.  Just think of a plant. When given proper care, nutrients, sunlight and the coolness of night, YOU then notice its growth and "beauty" the following morning, Yes??   Good luck. Let me know, after a month, and if you follow my advice, how it goes.  sincerely  Ken