“A normal metabolism is more than capable of handling long intervals between feedings.” If you need snacks to regulate blood sugar, “it means your metabolism is already in moderate disarray.”
Shanahan MD, Catherine (2011-04-22). Deep Nutrition: Why Your Genes Need Traditional Food.
Do Not Starve…Just Digest
Researcher and author James Clear’s says, “intermittent fasting is not a diet, it’s a pattern of eating. It’s a way of scheduling your meals so that you get the most out of them. Intermittent fasting doesn’t change what you eat, it changes when you eat. With all that said, the main reason people try intermittent fasting is to lose fat. This is a very good thing because it means intermittent fasting falls into the category of ‘simple enough that you’ll actually do it, but meaningful enough that it will actually make a difference.’”
James Clear continues to explain the scientific difference between starvation and the “fed state,” which is the foundation for the intermittent fasting reset. “Typically, the fed state starts when you begin eating and lasts for three to five hours as your body digests and absorbs the food you just ate. When you are in the fed state, it’s very hard for your body to burn fat because your insulin levels are high.”
Again, he points out how the body responds to sugar and its relationship with fat storage. He goes on to explain that letting your body fully digest the food allows your body to then burn fat because the insulin levels are low since there is no food coming into the body to be processed.
Success lies in giving your body at least a full 12-16 hour cycle of no food, which is contrary to the “craving to eat” feeling that repetitive and easy simple carb laden meals will emotionally pull you toward eating again. You are allowing your body to eat or use its fat stores and detox. The normal American eating habits and eating schedule does not allow your body to enter into this fat burning stage because not enough time has passed for your body to dip into its reserves.
When you’re in the fasted state your body can burn fat that has been inaccessible during the fed state.
Because we don’t enter the fasted state until 12 hours after our last meal, it’s rare that our bodies are in this fat burning state. This is one of the reasons why many people who start intermittent fasting will lose fat without changing what they eat, how much they eat, or how often they exercise. Fasting puts your body in a fat burning state that you rarely make it to during a normal eating schedule.
Improved cardiovascular disease risk profile
Several studies show intermittent fasting may lead to a reduction of total cholesterol by about 20 percent (7, 2, 4, 5, 10). This becomes even more impressive when we look at the breakdown of the effects on LDL, HDL, and triglycerides.
- LDL is the “bad cholesterol” (the worst is small, dense LDL, and the less offensive form is large, fluffy LDL).
- HDL is the “good cholesterol” (we don’t want to see HDL decrease, and most often we would prefer it actually increase).
- Triglycerides are a type of fat used to store excess energy from our diet, and high levels may be associated with cardiovascular disease and insulin resistance (we want low levels of triglycerides).
Since the total cholesterol on a blood panel is derived from a formula including LDL, HDL, and triglycerides, we want to make sure that a decrease in cholesterol comes from reductions in LDL or triglycerides, and not lowered HDL.
So, what happens to cholesterol with intermittent fasting?
Not only does LDL decrease by about 25 percent after eight weeks on an alternate daily fast, but even better, we actually see a decrease in small LDL particles (10, 11, 12). And remember, small, dense LDL particles are associated with an increased risk of cardiovascular disease when compared with an equal number of large, fluffy LDL particles. (Note: small, dense LDL is best viewed as a proxy for LDL particle number, which, as Chris explained here, is a more significant risk factor for heart disease than total or LDL cholesterol.) Thus, intermittent fasting favorably shifts LDL both by decreasing total LDL and also by decreasing the small, dense LDL particles.
And, as hoped, with intermittent fasting, there is no significant decrease in HDL (14).
Intermittent fasting is associated with decreases in inflammation
A study published this month investigated the effect of intermittent fasting on a marker of inflammation, specifically looking at NRLP3 inflammasome activation (15). The results indicated a decrease in this measure of inflammation with fasting.
Another study evaluated the effect of alternate-day fasting in adults with asthma and found a decrease in symptoms along with striking decreases in markers of oxidative stress and inflammation (7).
Intermittent fasting may improve brain health
A recent study investigated the effect of intermittent fasting on motor coordination skills, protein, and DNA damage in specific regions of the brain in middle-aged rats (16). This study also measured markers of cell metabolism, cell survival pathways, and synaptic plasticity (you can think of synaptic plasticity as a measure of the ability to learn).
The findings indicated that intermittent fasting was associated with improved motor coordination and learning response and a decrease in oxidative stress (think of oxidative stress as what we often consider “normal” age-related change). So, intermittent fasting may improve healthy aging of the brain and decrease the cognitive decline that is generally considered a normal part of aging.
Intermittent fasting may be associated with decreases in neuroinflammation
Chronic neuroinflammation is increasingly associated with neurodegenerative diseases like Alzheimer’s and mood disorders such as depression. One study published earlier this year looked at the role of intermittent fasting on markers of neuroinflammation in rats and found that this dietary approach actually changed gene expression to allow for an adaptive response (17). These results suggest that intermittent fasting may have a beneficial role in conditions associated with neuroinflammation.
While there are even more potential benefits to intermittent fasting, like improving insulin sensitivity and promoting a normal migrating motor complex (important in preventing SIBO as discussed here), I’ll have to save further discussion for another post to prevent this one from becoming too long. But hopefully at this point it’s clear that intermittent fasting can provide a number of measurable benefits.
There can be risks associated with intermittent fasting, and I would strongly recommend that it be pursued with the guidance of a qualified healthcare provider or nutritionist who understands the risks and benefits and can help determine if it’s right for you.
Intermittent fasting should always be avoided during pregnancy and breastfeeding and should generally be avoided during times of increased stress that contribute to Adrenal Fatigue Syndrome, or more precisely, hypothalamic-pituitary-adrenal (HPA) axis dysfunction.
Additionally, there are health risks associated with diets that are too low calorie, including concerns of nutritional deficiencies, electrolyte abnormalities, and potentially more serious risks if extreme diets are undertaken without appropriate supervision. Intermittent fasting can be a great strategy for weight loss and overall health during the right time for you and when approached cautiously.
Bottom line is that our bodies are not designed to eat all the time. The way our bodies consume fuel is very organized and specific. Humans historically did not always have food supplies available and so the amazing genetic ability for our bodies to store fuel as fat is imperative to the advancement of the species. This metabolic and physiological mechanism is key to losing weight and balancing your gut and brain communication…You do not need to eat all the time. The western diet fails not simply because of food choices, but because of behavior and habits that keep the body in a constant state of digestion and storage.
Change your behaviors and change your results.