I know that most low carb diets like Anabolic and Atkins require you to eat under 30 G of carbs a day to put you into fat burning mode. However, what happens if you consistently eat say 30 G - 100 G of carbs a day. Is your primary fuel source still Carbs?
I would say no. That's still not a lot of carbohydrate. Exercise habits/duration/stress levels will affect this though.
If you're attempting to enter ketosis, then yes the exact amount of carbs is going to be pretty important. I personally don't think that's the way to go, and you're better off with an insulin management plan. Ketosis usually has a strong catabolic effect, which makes it unsuitable for fat loss, even though the weight loss effects are strong.
I found my answer in an article from coach Thibs...
"People do not increase their fat intake enough. A lot of people don't limit themselves to a low-carbs diet; they also ingest very little fat. They reason that if they drop the carbs, their body will be forced to use fat for fuel, which is true. Where they go wrong is that they take their reasoning one step further and assume that if they cut off fat from their diet too, then they'll burn much more fat because the body will have to scavenge its own fatty acid reserve.
Now, this will, happen, to some extent. But the thing is that if one energy source is disproportionately high compared to the other ones, the body will adapt to use this fuel source are their main one.
So if your protein intake is way higher than the other nutrients, your body will become good at using protein for fuel. Since protein is an inefficient fuel source, the body will be quick to breakdown muscle tissue to produce the enery required: you'll be burning down the walls to heat the house!
So remember, when using a low-carb approach, fat intake should be high enough for your body to avoid turning into a protein-burning machine. During a proper low-carb diet your fat intake should be pretty close to your protein intake. Remember that 1 gram of fat has 9 calories while 1 gram of protein has 4. So 110g of fat is equal to 250g of protein. A 50/50 ratio (plus trace carbs) is a good place to start."