What constitutes a low carb diet?

I've been trying to limit daily intake of of carbohydrates in my diet to under 100g. Would limiting it even lower improve results in terms of weight loss?

Also, how many grams of carbohydrates does a normal male and female take as recommended by USDA guidelines?

  • 3
    <SoapBox>The USDA has a history of being absolutely HORRIBLE about making proclamations of what's "healthy". The US "Food Pyramid" is one of the only ones in the world (there are a few others, though) that have breads, pastas, and grains as the largest section. Most other countries have fruits and vegetables as the largest section, with grains and meats sharing the second. They teach it to you in school, and that's the recommendations that our parents feed their children (there are programs to help parents buy "healthy" food for their kids), and then look at our obesity rates.</SoapBox> May 29, 2012 at 16:02
  • This question is off topic now, regarding the FAQ.
    – Baarn
    Sep 12, 2012 at 18:26
  • 100g is 20% of your energy intake for someone who eats 2000kcal/day. If you want to stay in ketosis for most of the day, you'll have to eat less carbs than that, at least without exercise.
    – Mårten
    Jan 21, 2015 at 11:47
  • This question was asked before nutrition was deemed to be off topic. Please do not use it as an example of questions that are suitable to ask.
    – JohnP
    Feb 4, 2020 at 14:13

4 Answers 4


Depends on which low-carb diet you ask.


Normal guidelines aim for 45-65% of calories from carbohydrates.


Personally, I think you should just measure and see what works specifically for you--by definition, diet is really personal, and what works for any number of other people may not work for you.

I'm also leery of weight loss being a specific, absolute goal, but that's a separate issue.

  • Downvoter: reasoning behind downvotes, while not required, is appreciated. Aug 14, 2012 at 0:26
  • my apologies its me. I didn't mean to though :/. It won't let me vote up unless your 'edited' it apparently. If you want - switch a few words around or add a sentence and I can fix it.
    – Mike S
    Sep 14, 2012 at 6:00
  • +1 for being the best answer in this thread so far...
    – Marcus
    Feb 3, 2020 at 22:28

My low carbs diet is based on two rules:

  • Less than 20gr per day of carbs / sugar.
  • One day off to eat fruit and dinner pizza / thai / burger, etc.

I am 31 y.o. and a Software Engineer and doing sport for 3 days a week I loose aprox 1kg, per week.


Its hard to say as based on the classical low-fat/high-carb diet guidelines that have been popular for many years, being low carb 'in contrast' should be easily achievable. Basicaly its safe to say that unless you are doing high intensity workouts, your body can work quite nicely on zero carbs. If you are working out and you feel before the end of your workout that you have expended all of your energy, than yes, you will need some pre-workout carbs in your diet. In other cases you don't need any carbs but you might need some foods that come with carbs. The jury is still out over if you actually need dietary fibers but one thing that is sure, you need anti-oxidants and most of these come packaged with at least some carbs.

You should never just count grams of carbs, only percentages of calories or grams relative to the number of grams you take of other nutrients. A gram of fat holds 9 calories, a gram of carbs or protein 4. The total amount of calories should be dependent on your fat free body mass and on your level of physical activity. Basically the low range of what should be considered achievable low carb would have you at most 25% of your caloric intake from carbs. You should probably try to aim for 30% to 40% of your caloric intake from protein, so this means you should get at least 35% of your calories from fat.

If you can bring your carb consumption further down than by all means do so, but use this as starting point and keep track of your FFBM, body strength and work out endurance. Make sure you keep getting sufficient antioxidants and monitor how your body is doing. As long as you get enough antioxidants and as long as your FFBM, strength and endurance don't suffer, keep reducing your carb intake and moving carbs to pre-workout consumption untill you find your personal sweet spot.


Definition (answer s. str.)

"Low carb" usually means food that is low in starch and sugars.

Sugars are usually saccharose, glucose and fructose, although other sugars like maltose and mannose might be included as well.

Starch is food consisting of glucose chains, which means that your gut needs to break down the chains in order to take up the sugars.

Critique (extensive)

Personally, I'd rather go with the glycemic index than with "carb" or "no-carb". Because the glycemic index (GI) measures the blood sugar spike each food causes. The higher the GI, the more insulin is produced by the pancreas, which in turn increases blood sugar. And the higher the blood sugar, the more sugar is turned into fat by the liver. Lists of the GI index are here or here or look for one here (note that with natural foods these values can differ, but as with counting carbohydrates, the principle is more important than the values themselves).

Beside that, the processing of food is often quite important as the food itself, for instance the GI of oranges is 43, but the GI for orange juice is 50 (source). That's because processing usually breaks down complex carbohydrate chains into simple sugars, that explains the high GI of baked potatoes. But it also makes inedible food edible, since raw potatoes are toxic and grass can't be digested, yet if you process the grass you will get a fine and very healthy powder.

Finally, food constituents are taken up differently by each person, depending on his digestive system, his gut flora, his metabolism, his enzymatic predisposition (= genetic predisposition), aso. For instance some people's liver can transform sugars better into fat than those of other people. These need to take up less calories.


If you watch it historically, you can see that the diets were developing from the "Montignac diet" in the 90-ties to the "Whole Food diet" during the millenia years and now the trendy "low-carb diet". Funnily enough, the Montignac diet was heavily (but wrongly) criticized by M.D.'s, the Whole Food diet is criticized by the Paleo diet people (due to the "anti-nutrients" in whole foods, who could have guessed that), and there will also soon be a movement against the low-carb diet, if it's not already veganism (note: Whey is not vegan). This all happened while the M.D. stuck to just counting calories, which is probably the most inferior of the diets discussed above, but will still lead to a similar outcome in the long run. The next movement will be the "genetic food" movement: You'll test your genes for a few hundred bucks and then they can recommend certain foods for you in order to loose weight.

In the end, you just need to find something that works for you, because there are several roads that lead to Rome. And if that road is just for you without any name on it, then that's still good.

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