De Novo Lipogenesis- How Processed Carbs are Making us Fat and Sick
As is typical of so many busy parents, when my children were young I rarely had time to exercise and I ate the Standard American Diet, including boxed cereal, cupcakes for school parties, pizza on the weekend, and the occasional donut or croissant when at coffee with friends. Fast forward, and I found myself sitting in the liver doctor's office 30 pounds overweight and with the classic trifecta of metabolic diagnoses including non-alcoholic fatty liver disease, high cholesterol, and pre-diabetes. My very kind doctor told me that unless more significant liver disease and diabetes were my goals, I needed to lose the extra weight and to stop over-consuming refined carbs and sugars.
This scared me enough that my eating changed completely that day. I adopted a whole food, plant-predominant diet, and I've never looked back. All of my health issues have completely reversed and my weight has stabilized in the normal range without dieting or deprivation.
So why can eating too many simple carbohydrates
and ultra-processed foods lead to
fatty liver disease and high cholesterol?
The answer is a metabolic process called
De Novo Lipogenesis.
De Novo Lipogenesis literally means the creation (genesis) of new (de novo) fats (lipids)
from non-lipid sources, typically simple carbohydrates and sugars.
De Novo Lipogenesis is triggered when two conditions are present:
We are in an overfed state (when we eat too many calories for the amount of energy we expend).
We regularly consume simple carbs and sugars.
I created a handy-dandy map to try to make this process easier to understand.
Don’t worry, I’ll walk you through it.
The Steps of De Novo Lipogenesis
1. When we eat simple carbohydrates, these foods are broken down by digestion, mostly in the small intestine. The small intestine releases glucose, which is absorbed in the bloodstream and transported to the liver.
2. We use this glucose to fuel our immediate energy needs. Whatever is left over is absorbed by the liver, and through a process called Glycogenesis, it is converted into Glycogen. Glycogen is stored mostly in muscle cells and in the liver. Insulin secreted by the pancreas triggers both the production and storage of glycogen.
3. Once the liver's glycogen stores are full, any excess glycogen is converted into a molecule called Acetyl-CoA, which acts as a building block to create fatty acids.
4. Fatty acids are then combined with glycerol to create TAGs (Triacylglycerols). TAGS are more commonly known as Triglycerides. These are transported back to the liver.
5. However, the liver can only hold a small number of TAGs, so any excess TAGs are shuttled to our adipose (fat) tissues. These can be stored as subcutaneous fat (just below the skin) or as visceral fat (surrounding our organs).
6. When there is chronic overconsumption of calories, especially from simple carbohydrates and sugars, excess TAGs are created and storage in non-adipose tissues may be needed. Storage of TAGs in organs and tissues, such as the liver, that do not generally house large quantities of lipids is called Ectopic Fat Storage. Ectopic fat storage in the liver is associated with insulin resistance and non-alcholic fatty liver disease.
Non-alcoholic fatty liver disease (NAFLD) is traveling hand in hand with our growing global obesity epidemic. World estimates suggest that up to 25% of the global population may meet the criteria for NAFLD. The standard Western diet has been found to increase the risk of fatty liver disease by 56%. Eating like a typical American does no favors for our livers. As the liver gets fatty, there are a number of downstream impacts including insulin resistance, diabetes, and increased cardiovascular risk. For more information on fatty liver, please see: www.thewell-nourishedbrain.com/blog/foods-for-a-healthy-liver
7. When combined with insulin, the liver can also use the Acetlyl-CoA produced from glycogen to synthesize cholesterol. Excess cholesterol is associated with conditions such as heart disease, type 2 diabetes, metabolic syndrome, and dementia.
When we are chronically overfed
and we then consume simple carbohydrates
(like white flour and sugar, ultra-processed foods,
and sweetened drinks),
we can trigger De Novo Lipogenesis.
This promotes obesity, non-alcoholic fatty liver disease,
metabolic syndrome, insulin resistance,
type 2 diabetes, cardiovascular disease,
and even dementia.
How Do We Inhibit De Novo Lipogenesis?
Being in an overfed state is a necessary condition for triggering De Novo Lipogenesis (DNL). When we eat simple sugars, but there is not an excess of overall calories consumed, DNL is not initiated. However, when we consume more calories than we burn, as so many individuals eating the hyper-caloric Standard American Diet do, and the liver is then bombarded with simple carbs and sugar, the excess glucose is turned into fat through DNL.
So, our first step is to try to balance our energy input with our energy expenditure. When we expend as many calories as we consume, we are considered to be in a state of energy balance. If we are in a state of energy balance, DNL is not triggered and no new fat is made.
But how do we achieve a state of energy balance? We move a little more (nothing crazy, maybe an extra 15 minute walk a day) and we focus on eating foods that are low in calorie density. Eating a low calorie density diet is the key to achieving energy balance and maintaining a healthy weight without dieting or deprivation.
For a refresher on calorie density, please see:
www.thewell-nourishedbrain.com/blog/calorie-density
We stop regularly consuming simple carbs and sugars, like chips, pastries, candy, crackers, cookies, and foods made from refined white flour and sugar. As processed fructose is particularly lipogenic, it is especially critical that we avoid anything sweetened with high fructose corn syrup, like soda, juice drinks, fast food, some condiments, jams and syrups, and many processed meats. Manufacturers are sneaky about making foods tastier using high fructose corn syrup, so be sure to read labels.
We stop eating the hyper-caloric Standard American Diet. It is terribly difficult to maintain balanced energy expenditure if we are eating a diet that is nutrient-poor and calorie-rich. Ultra processed foods have been shown to be hyper-palatable and highly addictive, while leaving us in a state of nutrient deficiency. It is almost impossible to exercise enough to burn off the overly caloric ultra-processed Western diet. For more information on ultra-processed foods and hyperpalatablity, please see: www.thewell-nourishedbrain.com/blog/ultra-processed-and-hyper-palatable
We eat a diet high in fiber and phytonutrients. Researchers have found that a diet rich in beneficial dietary components (such as fiber, polyphenols, Omega-3 fats, and antioxidants) reduces liver fat accumulation through the inhibition of de novo lipogenesis (Constabile et al., 2022; Green et al., 2020). Opting for complex high-fiber carbohydrates (such as whole grains, legumes, and a wide array of fruits and vegetables), and prioritizing fat sources containing Omega-3s (such as nuts, seeds, avocado, and fatty fish), will help to inhibit de novo lipogenesis and lower our risk of developing fatty liver disease, insulin resistance, type 2 diabetes, heart disease, and dementia.
To protect your liver and prevent de novo lipogenesis, start with these baby steps:
Center your diet around foods that are low in calories and high in nutrients and fiber (veggies, fruit, potatoes, whole grains, and legumes).
Prioritize sources of healthy unsaturated fat such as nuts, seeds, avocados, olives, and fatty fish, eating these in moderation.
Remove temptation from your environment by keeping processed junk out of the house.
Find replacement foods for your favorite processed snacks. For salty cravings, try air popped popcorn, salted edamame, pickles, or baked potato wedges. For sweet cravings, try popsicles made from fresh fruit, banana “nice” cream, or dark chocolate.
If this all sounds overwhelming, know that it is achievable with small consistent changes.
Making a conscious decision to prioritize your health is the first step.
The rest is just learning new patterns of behavior.
If I can do it, so can you!
Wishing you abundant good health and happy eating!
🌱💕
References:
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