Jimmy Moore has a great post defining different levels of low-carb diets. This is something that has bothered me for a while: when someone says “low carb” you don’t necessarily know what they mean. I’ve seen research studies refer to diets with 45% carbs as low carb! That may well be low compared to the standard American diet, but it’s a lot more carbs than on Atkins, etc.
Last year, a number of researchers discussed carb restriction as an approach to treating diabetes and metabolic syndrome, and as part of that discussion, laid out the following definitions:
The ADA designates low carbohydrate diets as less than 130 g/d or 26% of a nominal 2000 kcal diet and we consider this a reasonable cutoff for the definition of a low-carbohydrate diet. Carbohydrate consumption before the epidemic of obesity averaged 43%, and we suggest 26% to 45% as the range for moderate-carbohydrate diets. The intake of less than 30 g/d, as noted above should be referred to as a very low carbohydrate ketogenic diet (VLCKD).
In the December 2008 issue of Clinical Nutrition Insight, a subset of the study authors added the low-carb ketogenic diet to acknowledge the difference between the LCKD and the VLCKD diet; the latter is generally a therapeutic approach for epilepsy.
Thus we have:
- Very low-carb ketogenic diet (VLCKD): < 30g carbs/day
- Low-carb ketogenic diet (LCKD): < 50g carbs/day
- Low-carb diet (LCD): 50-130g carbs/day
- Moderate-carb diet (MCD): 130-225g carbs/day
For the average person eating 2000 cals/day, this represents 6%, 10%, 10-25% and 26-45% of the diet, respectively.
BTW, I agree entirely with Jimmy on this:
The bottom line for you and me is to find out at what level carbohydrate-restriction is necessary for managing your weight and health. Some may be able to eat a MCD while others like me need to stay on a LCKD. Discover what works for you, follow it exactly and then stick to it for life!
And for some, that might even include a high carb or maybe even zero carb diet! See Jimmy’s post for lots more interesting info.
Weight Maven is written by Beth Mazur. Beth believes that obesity is more symptom than cause and that the real problem is our modern culture -- especially diet. Beth writes about ancestral health, health policy, & mindfulness. And cats! 
I feel best and maintain the healthiest weight on an isocaloric (33/33/33), no-processed-crap regimen. That would put me in the low/moderate range for carbs and is consistent with things like Atkins OWL and/or maintenance.