Combat Aging & Improve Insulin Sensitivity

As we age, longevity naturally becomes more of a concern. Indeed, last year, Americans spent over 5.2 billion dollars on efforts to ensure they can live as long as possible [1]. 

Many have turned to exercise, supplements, stress management, and meditation in the quest to lengthen their lives. Some go to even more extremes, such as cold immersion therapy [2]. However, in the pursuit of longevity, the importance of diet–particularly an insulin-sensitizing diet–cannot be overstated. 

Insulin resistance is profoundly linked to deadly diseases, such as cardiovascular disease, diabetes, non-alcoholic fatty liver disease, Alzheimer’s, metabolic syndrome, sleep apnea, and more. Even in non-diabetic individuals, insulin resistance is associated with all-cause mortality [3]. 

Any efforts to increase longevity, then, should focus first on becoming more insulin sensitive. Let’s take a look at the connection between insulin resistance and aging, and then we’ll review the best diet to address aging.

Why Does Insulin Resistance Increase With Age?

Several factors contribute to an age-related increase in insulin resistance:

1. 1. Changes in Body Composition: As people age, they often experience changes in body composition, such as increased fat mass and decreased muscle mass [4]. Higher levels of body fat, especially visceral fat (fat around the organs), are associated with a higher risk of insulin resistance [5].
   2. Decreased Physical Activity: Aging frequently leads to a decrease in physical activity, which can contribute to weight gain and muscle loss. Regular physical activity helps maintain muscle mass and can improve insulin sensitivity [6].
   3. Hormonal Changes: Both men and women experience changes in both growth and sex hormone levels as they age, and these changes influence how the body responds to insulin. Lower levels of growth hormone can contribute to decreased muscle mass and an increase in body fat, particularly visceral fat. In men, a decrease in testosterone levels can lead to increased insulin resistance, just as declining estrogen levels during menopause can contribute to insulin resistance in women [7].
   4. Inflammation: Aging is associated with a chronic, low-grade inflammatory state known as “inflammaging. [8]” Inflammaging is characterized by an increase in the production of pro-inflammatory cytokines and other immune factors, even in the absence of an overt infection [9]. Chronic inflammation can interfere with normal insulin signaling and contribute to insulin resistance [10].
   5. Mitochondrial Dysfunction: Mitochondria, the powerhouses of the cell, may become less efficient with age. Mitochondrial dysfunction can lead to decreased cellular energy production and impaired insulin sensitivity [11].
   6. Oxidative Stress: Aging is also associated with increased oxidative stress, which can damage cells and impair their function, including their response to insulin [12]. Oxidative stress is an imbalance between the production of free radicals (reactive oxygen species) and the body’s ability to counteract or detoxify their harmful effects with neutralizing antioxidants. 
   7. Changes in Fat Cells: As we go through infancy, childhood, and puberty, the number of fat cells we have rises, until it essentially flatlines for the rest of our adulthood. When we gain fat, it is a function of the fat cells themselves growing [13]. That becomes relevant as we age, because when we get to around our 60s or 70s, the number of fat cells we have starts to decline. However, if we continue to eat the same way that had us store a certain amount of fat, the remaining fat cells will simply get bigger and bigger. The bigger the fat cell gets, the more insulin resistant and pro-inflammatory it becomes, making the rest of the body insulin resistant.

After looking at this list, it’s natural to wonder two things: What is an insulin-sensitizing diet? And how can I start?

What is an Insulin-Sensitizing Diet?

An insulin-sensitizing diet is a way of eating that focuses on stabilizing blood sugar levels and improving the body’s response to insulin.

Insulin, a hormone produced by the pancreas, plays a crucial role in regulating glucose levels in the blood. When you consume carbohydrates, your body breaks them down into simple sugars, like glucose, which then enter the bloodstream. In response, the pancreas releases insulin to signal cells to either use this simple sugar as immediate energy, store it in the liver and muscles as glycogen, or store it as fat.

For insulin sensitive people, only a small amount of insulin is necessary to keep this essential process happening. But the more a body is subjected to a hormone, the more resistant it becomes to it. As an individual keeps eating carbohydrates, the body produces more and more insulin, which in turn leads to more and more stored fat and, eventually, insulin resistance.

How Can I Start an Insulin-Sensitizing Diet?

The most effective insulin-sensitizing diet is the ketogenic diet, although eating a low carbohydrate diet is also effective. The goal of a keto diet is to keep your carb intake very low–typically under 50 grams of net carbohydrates per day–so that your body enters a state of ketosis and burns its own stored fat for fuel [14]. 

Ketogenic and low carbohydrate diets are famous for weight loss (shrinking fat cells), but restricting net carbs offers a number of cardiometabolic and anti-inflammatory health benefits [15,16,17]. Keto diets are also known to repair oxidative stress, to protect against muscle loss, and to improve mitochondrial function [18,19]. All of these benefits lead to increased longevity.

If you’re pursuing a diet that will help you live healthy and live longer, look to three simple pillars:

Control carbohydrates 

Because refined, simple carbohydrates spike blood sugar the most, they also cause the biggest spike in insulin. Focus on whole fruits and vegetables when consuming carbs.

Prioritize protein 

Protein is vital to human nutrition and has little to no effect on insulin, especially when consumed with fat in a 1:1 ratio. 

Don’t fear fat

Fat alone has no effect on insulin, and it often comes with the best proteins. Animal fats and fruit fats (like olive, coconut, and avocado) are your best options for healthy fats. Avoid vegetable and seed oils, as they are pro-inflammatory and are associated with heart disease and insulin resistance [20,21].

Aging is inevitable, but eating better can help us age better, too.

References

1. https://fortune.com/well/2023/08/10/wealthy-americans-extreme-measures-to-live-longer/
2. https://www.nature.com/articles/s43587-023-00383-4
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2875420/
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6970947/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4038351/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6304477/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6604485/
8. https://pubmed.ncbi.nlm.nih.gov/11303144/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146930/
10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1483173/
11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2963150/
12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398902/
13. https://pubmed.ncbi.nlm.nih.gov/37725294/#:~:text=Aging%20changes%20the%20distribution%20of,of%20insulin%20resistance%20and%20T2D.
14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7705738/
15. https://pubmed.ncbi.nlm.nih.gov/34448957/
16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716748/
17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5981249/
18. https://www.sciencedirect.com/science/article/pii/S2667394023000072
19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9762714/
20. https://pubmed.ncbi.nlm.nih.gov/23386268/
21.  Simopoulos, A. P., Is insulin resistance influenced by dietary linoleic acid and trans fatty acids? Free radical biology & medicine 1994, 17, (4), 367-72.