While it's true that the Biblical accounts of diet did include fruits, grains, vegetables and meat it says nothing about the proportions in which those foods were eaten. Was it equal portions of each, heavy on the meat, heavy on the fruits and veggies or heavy on the grains? I'd also like to point out that the "Biblical" diet isn't necessarily a guarantee of good health. Obesity was not unknown even then (take Eli the priest, for example). When mummies from Egypt are examined from that time period, they found evidence of obesity and heart disease and those folks weren't exactly eating Twinkies and Ding Dongs, either. With the exception of grains that could be stored, the fruits and vegetables that were eaten were dependent on what was in season and on what you could grow yourself or afford.
What we do know is that even though all the food groups were eaten, those that ate them also lived a very strenous lifestyle. The average person worked hard from morning to night at physically demanding tasks. They walked pretty much everywhere they went unless you were wealthy enough to own a donkey. Today, most of us don't live those kinds of lifestyles, so it's difficult to apply that type of eating pattern to a culture that is much more sedentary. I could probably get away with eating a lot more carbs than I do if I were to get a job that involved heavy physical exertion for 10-12 hours a day and walked everywhere I went too.