Jonathan, Can you tell me what is happening in nside my body like cholesterol or kidneys cleaning out and what does that do for you.
Jack is on a juice fast. He’s been going almost two months strong.
Here’s my take on what juice fasting does to your body on a cellular level, specifically with regards to cholesterol.
Disclaimer: I am NOT a doctor! So what I’m about to say does NOT constitute medical advice! If you have specific medical questions then please consult your licensed health professional.
What Juice Fasting Does For Your Health
For those of you that aren’t aware, juice fasting is when you drink condensed fruits and vegetables as your sole source of calories for some period of time. Most people do it for 3-7 days. Jack’s doing it for much longer.
There is NOT a lot of specific studies on what juice fasting does to your health. In fact there are practically none. However, there ARE lots of studies on what juice fasting is: nutrient dense caloric restriction. Caloric restriction is when you drastically reduce the calories your body needs while still giving it the necessary nutrients.
It’s the closest thing there is to a fountain of youth.
The benefits of caloric restriction include:
- reduced body weight
- lower incidence rates of cancer and atherosclerosis
- lower blood sugar and insulin levels
- increased lifespan
What’s more, the benefits of caloric restriction have shown to be robust to practically any life form. Even bacteria do a lot better when they’re starved.
So with that said, let’s take at how and what juice fasting might do specifically for your cholesterol.
A Quick Primer on Cholesterol
Cholesterol is made by your body and comes through your diet and is used to help metabolize and transport different fatty acids, is the basis for bile acid, steroids like estrogen and testosterone, and provides structure to cell membranes. It’s important stuff.
For the most part the regulation of the cholesterol in your body is controlled by the level of cholesterol in your body. Its presence turns different enzymes and metabolic pathways on and off, which in turn allows your body to ramp up or ramp down your levels of cholesterol as needed.
However, long term dietary habits can nudge your body’s serum cholesterol levels up or down in a more permanent direction that can be harmful. There’s decent reason to think that juice fasting (caloric restriction) can help you in that goal…..at least in the long run.
In the short run it’s not as clear.
How And Why Drastically Reducing Calories Affects Your Cholesterol Levels
Low calorie, nutrient dense diets do at least two things which affect your cholesterol levels
- It drastically reduces the adipose (fat) tissue in your body
- It reduces the levels of insulin in your body and your sensitivity to it
A lot of the functions of cholesterol have to do with the storage and transportation of different types of fat. Fat cells/tissue have a tendency to secrete various hormones which tell your body to store more of it.
Your body operates under the assumption of scarcity, so it assumes that it should stock up on fat if it’s cheap. The presence of fat tissues and the different metabolic chemicals it secretes seem to promote the synthesis of cholesterol…..at least to some degree.
However, the more important issue seems to be how caloric restriction affects your body’s sensitivity to insulin.
Insulin is the chemical that tells your body to scoop up sugar from the blood and to stop using fat for energy. It also promotes the production of an enzyme called HMGR which enables cholesterol to be made from its precursor Acetyl-CoA.
Permanently elevated levels of insulin results in a lot of extra HMGR floating around in your cells, which leaves your body’s level of cholesterol production permanently higher and insensitive to changes in your diet.
The picture below is what happened to the insulin levels of male and female rhesus monkeys who reduced their caloric intake by 30% over a 6 year period:
Prolonged juice fasting reduces insulin concentrations and improves insulin sensitivity, which is a problem for people who have a diet that consists primarily of quickly digested refined foods.
Juice Fasting and Cholesterol Levels In The Short Run
So juice fasting/caloric restriction improves your insulin balance and gets rid of fat, which is great.
However, these effects happen over the long run.
In the short run juice fasting actually might increase your cholesterol levels.
It might sound paradoxical, but it’s a logical consequence of the different metabolic effects caloric restriction has on your body.
Caloric restriction reduces oxidative stress and the metabolic “cost” of maintaining your body, which causes your body to cool down and your metabolic rate to slow down somewhat. Cholesterol is metabolized in your cells by being “turned over” by lipoproteins (LDL and HDL). The decrease in metabolic rate slows this process down which causes your cholesterol levels to stay the same.
In fact, it might actually reduce HDL cholesterol levels in the short run, which is the “good” kind. For example, a study published in the American Journal of Clinical Nutrition found that 47 males had unchanged LDL cholesterol levels and significantly lower HDL cholesterol after undergoing caloric restriction for 10 weeks.
So take note that juice fasting all by itself is not a prescription to lower your cholesterol for a few months. It’s a wonderful thing, but it’s not a statin and shouldn’t be used like one.
I’ve written before that it’s a mistake to think of a juice fast as a “one-off” event. Fasts are wonderful for your health, and a juice fast ensures that your fast will be packed with awesome nutrients, ensuring its maximal benefit.
Juice fasting is an occasional nutritional burst you should subject your body to help reset itself. It should not be approached like a marathon. That one time, grueling event that you need to complete no matter what.
Heilbronn, Leonie, et. al. “Calorie restriction and aging: review of the literature and implications for studies in humans”
Fontana, Luigi, et. al. “Long-term calorie restriction is highly effective in reducing the risk for atherosclerosis in humans”
Lane, M.A. et. al. “Calorie Restriction in Nonhuman Primates: Effects on Diabetes and Cardiovascular Disease Risk”
Weltman, Arthur, et. al. “Calorie Restriction and/or Mild Exercise: Effects on Serum Lipids and Body Concentration”
Kudchodkar, Bhalchandra J., et. al. “Effects of Acute Caloric Restriction on Cholesterol Metabolism In Man”
Holloszy, John, et. al. ”Caloric Restriction In Humans”