where does the 30 grams or less come from

[heaviestj]

Most people I know doing keto are on 30 grams or less. Why 30? At what point does a body stop ketosis as far as grams of carbs? I'm interested in the science is all. No problem staying at 20~30 grams so far.

[driungis]

Vegetables overrated. If any carbs it used come frome vegies. Also dairy nuts seeds any sauces everything adds up. I used to sit 5-10g carbs, eating fatty cuts, mct, olive oils, eggs bf coffe, a chance that your overall calories is high, and you consuming more food in general that's how carbs go up. You can go way lower than typical keto calculator tells you. If you fast it makes esier to control the food

[aygung]

depending on your body's adaptiveness to ketosis some people go up to 80-100 grams / day too. (getting to this point takes a while tho a few months at least) and if u aren't in ketosis by then a HIIT session before hitting the weights gets you in ketosis again. (right when it is needed)


for the science part, I found a nice read; (copy/paste)

Arguably the two most critical aspects of a successful carb-load are the duration of the carb-load and the total amount of carbohydrates consumed during this time period. In brief, to achieve optimal glycogen levels, both the duration of the carb-load and the amount of carbs eaten must be correct. The rate limiting step in glycogen resynthesis appears to be activity of the enzymes involved in glycogen synthesis (1). Regardless of carbohydrate intake, there is a maximal amount of glycogen which can be synthesized in a given amount of time. That is to say, consuming all of your carbohydrates in a 4 hour time span, with the goal of returning to ketogenic eating that much sooner, will not work. Only when the proper amount of carbohydrates is consumed over a sufficient period of time, can glycogen compensation and/or supercompensation occur. Following exhaustive exercise and full glycogen depletion, glycogen can be resynthesized to 100% of normal levels (roughly 100-110 mmol/kg) within 24 hours as long as sufficient amounts of carbohydrate are consumed (1,2). Assuming full depletion of the involved muscles, the amount of carbohydrate needed during this time period is 8-10 grams of carbohydrate per kilogram of lean body mass (8-10 g/kg). With 36 hours of carb-loading, roughly 150% compensation can occur, reaching levels of 150-160 mmol/kg of muscle glycogen. To achieve greater levels of muscle glycogen than this (175 mmol/kg or more) generally requires 3-4 days of high carbohydrate eating following exhaustive exercise (3). It should be noted that carb-loading has primarily been studies following endurance training, not weight training and there may be differences in how the body handles carbs following weight training. The first 6 hours after training appear to be the most critical as enzyme activity and resynthesis rates are the highest, around 12 mmol/kg/hour (4). Following weight training, with a carbohydrate intake of 1.5 grams carbohydrate/kg lean body mass taken immediately after training and again 2 hours later, a total of 44 mmol/kg can be resynthesized (4). Over the the first 24 hours, the average rate of glycogen resynthesis ranges from 5-12 mmol/kg/hour depending on the type of exercise performed (5). In general, aerobic exercise shows the lowest rate of glycogen resynthesis (2-8 mmol/kg/hour), weight training the second highest (1.3-11 mmol/kg/hour), and sprint training the highest (15 to 33.6 mmol/kg/hour). (5,6). The reason that glycogen resynthesis is lower after weight training than after sprint training may be related to the amount of lactic acid generated as well as the muscle damage that typically occurs during weight training (5). At an average rate of 5 mmol/kg /hour, approximately 120 mmol/kg of glycogen can be synthesized over 24 hours. This can be achieved with the consumption of 50 grams or more of carbohydrate every 2 hours during the first 24 hours after training. Intake of greater than 50 grams of carbohydrate does not appear to increase the rate of glycogen synthesis. Over 24 hours, at 50 grams per 2 hours, this yields 600 grams of carbohydrates total to maximize glycogen resynthesis. These values are for a 154 pound (70 kilogram) person. Significantly heavier or lighter individuals will need proportionally more or less carbohydrate. Simply keep the value of 8-10 grams of carbohydrate per kilogram of lean body mass as a guide. In the second 24 hours, glycogen resynthesis rates decrease (1) and a carbohydrate intake of 5 grams/kg is recommended to further refill muscle glycogen stores while minimizing the chance of fat gain. For many individuals, the small amount of additional glycogen resynthesis which occurs during the second 24 hours of carbohydrate loading is not worth the risk of regaining some of the bodyfat which was lost during the preceding week.

References
1. John Ivy “Muscle glycogen synthesis before and after exercise” Sports Medicine (1991) 11: 6-19.
2. William M. Sherman “Metabolism of sugars and physical performance” Am J Clin Nutr (1995) 62(suppl): 228S-41S.
3. “Physiology of Sport and Exercise” Jack H. Wilmore and David L. Costill. Human Kinetics Publishers 1994.
4. Pascoe D.D. et. al. “Glycogen resynthesis in skeletal muscle following resistive exercise” Med Sci Sports Exerc (1993) 25: 349-354.
5. Edward F. Coyle “Substrate Utilization during exercise in active people” Am J Clin Nutr (1995) 61 (suppl): 968S-979S.
6. D.D. Pascoe and L.B. Gladden “Muscle glycogen resynthesis after short term, high intensity exercise and resistance exercise” Sports Med (1996) 21: 98-118.


from this info, you can even calculate how much carbs you can get for yourself without replenishing your glucogen reserves and get out of ketosis

[JWoodCF10]

In simplistic non-scientific terms.

It comes from Atkins. His induction phase in 1972 was 30 gm or less per day.

Everyone now sticks to it as it is a good guide point.

I am fairly sure he did a fair bit of work to decide on that point, but I for one have never looked in to it.

I personally stick to 20 gm or less, and work on total carbs not sugars. Makes life easy for me.

[grndzro]

I just eat more protein if I am working hard and just rely on Gluconeogenesis for my blood sugar.
Fk carbs all they do is screw me up.

[Shenpen]

Most people I know doing keto are on 30 grams or less. Why 30? At what point does a body stop ketosis as far as grams of carbs? I'm interested in the science is all. No problem staying at 20~30 grams so far.

"...The results indicated that composition of weight lost during the VLCARB and the mixed diet
was water 61.2, fat 35.0, protein 3.8, and water 37.1, fat
59.5, protein 3.4 percent, respectively...

After nine weeks on the 30-g, 60-g and 104-g carbohydrate diets, weight loss was 16.2, 12.8 and 11.9 kg and fat
accounted for 95, 84, and 75% of the weight loss, respectively."

[abidur88]

i go up to 40 or 50 carbs per day but still seem to be in ketosis so i guess its just tolerance and how your body works.