In 1920,ketogenic was introduced by doctors to treat epilepsy by mimicking
the metabolism of fasting. Which turns out to be one of the most effective treatments in a handful of children’s hospitals. However, over the past 15 years, scientific interest has increased. Since at least 500 BC, fasting and other dietary regimens have been used to treat epilepsy.PMID: 19049574
When the body (Liver) breaks down fats in to
- acetone
- acetoacetate and
- beta hydroxybutyric acid(BHB)
these acids are known as ketone bodies, and the process of keep making these ketone bodies is known as ketogenic.
Ketones are water-soluble; hence, the liver can easily release them into the blood. In the body, when glucose is insufficient, ketones replace it as fuel for organs and tissues.
Basically, by limiting carbohydrates, the body shifts to burning dietary and body fat for energy, and ketones are produced as an alternative energy source.
When carbohydrate intake falls below 50 grams per day, the body prefers to utilize either dietary or stored fats for energy. This process increases when carbohydrates are below 30 grams or more, resulting in an increase in the level of ketones in the blood.
This number is from a group of scientists who are known for their work on low-carb diets.PMID: 17684196 PMID: 23266565
Ketone levels and fat loss are not correlated. In other words, higher ketone levels do not mean greater fat loss.
Some studies have suggested that a ketogenic diet may decrease the activity of hormone-sensitive lipase, potentially leading to reduced fat breakdown and utilization. The reasoning behind this hypothesis is that when the body is in a state of ketosis (where ketone bodies are produced from fat breakdown), the reliance on stored fats for energy might decrease the need for immediate fat mobilization through hormone-sensitive lipase.
However, other research has indicated that a ketogenic diet may actually increase the activity of hormone-sensitive lipase. This could be because ketogenic diets are often high in fat, which could stimulate lipolysis (the breakdown of fats) and subsequently lead to increased HSL activity.
The effects of a ketogenic diet on hormone-sensitive lipase and fat metabolism are likely influenced by various factors, including an individual’s metabolic state, specific dietary composition, duration of the diet, and the body’s adaptation to ketosis.
In 2015, a systematic review and meta-analysis showed that people who ate as much or as little as they wanted on a keto diet reported a decrease in feelings of hunger and desire to eat further. PMID: 25402637 People who eat fewer carbohydrates and more protein feel more satiety further more Ketones may also have an appetite-reducing effect, but up to what extent is still a question mark but the appetite-suppressing effect may decrease with time.PMID: 29105987
PMID: 23651522
Ketosis is a state of the body which is generally defined as >0.2 mmol/L, but most studies use ≥0.5 mmol/L as their practical threshold otherwise under normal, carbohydrate diet conditions, it is 0.1 millimoles of ketones per liter of blood, or less ≤0.1 mmol/L.
It can be measured by ketone levels via a blood, breath, or urine test. A blood test for βHB which may vary between 0.2 – ≥0.5 mmol/L which can be taken at any time and is more precise, accurate, and reliable than a breath or urine test which shows current ketone production. But readings can mislead due to caloric deficit or if taken during or after exercise, due to exercise increases ketone production and utilization.
A breath test can be taken at any time which shows current ketone production. Readings can vary depending on many factors, such as weight loss, a sudden change in carb intake (Cyclical Ketogenic Diet or Targeted Ketogenic Diet), Exercise, caloric deficit or simply how much breath is exhaled. So, it’s not as accurate as blood tests, but it’s pretty close. The breath test measures the acetone which is excreted through breath called “keto breath”, an odor which smells like “nail polish remover” and “slightly fruity”.levels of 4–30 ppm, which is corresponded to Blood βHB levels of 0.5–3.0 mmol/L.PMID: 26524104
A urine test can be usually taken in the morning, before breakfast, or late in the evening, at least two hours after the last big meal or at least two hours after exercise. Readings can vary depending on many factors like caloric deficit, hydration due to fluid intake and if a strip doesn’t change color, it may have become defective due to moisture. Hence, a urine test gives only approximate ketone levels which doesn’t reflect what your ketone levels are, but rather what they were an hour or so ago. It is measured by the chemically coated paper strip (very small, inexpensive and portable) which changes color. Then the user needs to compare the strip’s color to a color chart typically printed on the bottle quickly because the strip’s color can keep changing after exposed to urine.PMID: 27822291
Likewise, it is not necessary to test ketones, but doing so can provide a baseline for ketone levels. This can be used to adjust “carb threshold”(as low as 30 grams or as high as 80 grams) in line with them, depending on the individual.
Ketone levels vary due to production (ketogenesis) and utilization (ketone uptake by your tissues) even if diet doesn’t.
Moreover, there is a difference between nutritional ketosis and ketoacidosis. Ketoacidosis, a life-threatening medical condition where blood ketone levels exceed 12–15 mmol/L and one can’t reach such high levels just by ketogenic diet.
In 2021 systematic review and meta-analysis study (13 RCT) showed that KDs significantly decreased Body mass (1.4kgs) even with resistance training compared to non-KDs. However, adherence to KDs may negatively impact FFM, which is not improved by the addition of resistance training.PMID: 33624538
Lean body mass loss may have been mostly body water. It’s hard to know whether the subject lost contractile tissues.
Non KD showed significant increases in Bench Press, squat and countermovement jump compared to KD, PMID: 32276630. This might be because KD subjects gain less muscle tissue due to protein imbalance. Carbohydrates inhibit muscle protein breakdown due to the effect of Insulin on proteasome also int ital week in KD, there is an increase in loss of nitrogen in the body from urine. PMID: 27385608.