There is without a doubt conventional wisdom about metabolism. It goes something like, “Most people gain weight each year no matter what because their metabolisms slow down, especially around middle age.”.
We’ve also been told that women have slower metabolisms than men. Menopause only makes things worse, slowing women’s metabolisms even more.
Turns out, none of this is true.

A study done a few year ago, published in Science, using data from 6,400 people across the world, ranging in age from 8 days to 95 years old, had some results that have changed how experts think about metabolism.
The shocking results of this study were made possible because they were able to use regression analysis to remove any excess body fat from each person. Not only did they find that there are no real differences between the metabolic rates of men and women after controlling for other factors, but the results also showed something that had never been identified - four distinct phases of human metabolism based on age.

The four phases of metabolism:

    Infancy (Up to 1 year): Metabolism is at its highest, burning calories at a rate about 50% higher than adults. Babies absorb everything. Everyone loves a fat baby, right?

    Adolescence (1 to 20 years): The metabolic rate gradually slows by about 3% each year until it reaches adult levels around age 20. Despite the teen years being a time of growth spurts, the researchers didn’t see any uptick in daily calorie needs in adolescence after they took body size into account.

    Adulthood (20 to 60 years): The metabolic rate remains stable, even through major hormonal changes like pregnancy and menopause. We are hardwired for our metabolism to be stable through the majority of our adult life. While several factors could explain the thickening waistlines that often emerge during our prime working years, the findings suggest that a changing metabolism isn’t one of them.

    Older Adulthood (After 60 years): The metabolic rate begins to decline, slowing by about 0.7% to 1% per year. This decline is likely linked to a general slowdown in organ function. Energy requirements of just the heart, liver, kidney and brain account for about 65% of your resting metabolic rate.  The slowing of your metabolism at age 60 is likely then linked to your organs not functioning as well as they should.  The authors go so far as to note that despite how ‘young’ a person looks in their 60’s, biologically their organs are likely not functioning nearly as well as they had previously. Getting old is just never going to be easy on your body!

There are more than 80 co-authors on the study. They combined data from six different labs collected over 40 years. All of the research centers involved in the project were studying metabolic rates with a method considered the gold standard — doubly labeled water. It’s a urine test that involves having a person drink water in which the hydrogen and oxygen in the water molecules have been replaced with naturally occurring “heavy” forms and then measuring how quickly they’re flushed out. The investigators also had participants’ heights and weights and percentage body fat, which allowed them to ultimately factor in someone’s excess fat and muscle mass when it came to calculating their actual metabolism.

Many people still see their weight increase as they get older, despite their metabolism staying relatively the same throughout their life. This suggests that weight gain isn’t a result of slowing metabolism. Rather, it’s more likely to be due to eating more food than our body uses. What else contributes to weight gain?

Primary factors to weight gain as we age are:

Muscle loss (Sarcopenia): Starting around age 30, adults lose about 3–8% of muscle mass per decade. Muscle burns more calories at rest than fat, so less muscle mass means fewer calories are burned throughout the day.

Reduced physical activity: People tend to become less active as they get older, which lowers overall daily energy expenditure. They usually do not adjust food intake accordingly.

Poor sleep: Your body continues to perform essential functions overnight, requiring energy (45-55 calories per hour) to do so. This includes repairing cells, processing nutrients, and maintaining a core body temperature.

Fat storage: Excess body fat crushes our metabolism. The body's ability to burn fat for energy is reduced, while its capacity to store fat increases, creating a cycle that favors further weight gain

Medications: Some medications can promote weight gain.

Remember that all of these findings were after controlling for the amount of fat free mass people have - pretending people were all lean - and then comparing.  

The study shows that less fat that you have, regardless of age, the more energy you expend. 

Unfortunately, neurological conditions are back in the news due to several celebrities making public their struggles with disorders such as epilepsy, Alzheimer's, ALS, Dementia and Aphasia. Neurological disorders are medically defined as disorders that affect the brain as well as the nerves found throughout the human body and the spinal cord. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms.

The specific causes of neurological problems vary, but can include genetic disorders, congenital abnormalities or disorders, infections, lifestyle or environmental health problems and injuries to the head or spinal cord.

The “lifestyle or environmental health” causes are the ones that are most fascinating to me. These can be controlled and have been studied quite a bit over the last few years. Some of the evidence should be alarming to everyone but seems to go unnoticed.

I determined long ago that I wanted to do all that I could to maintain my physical abilities as I aged. It’s no secret that physical decline begins in the decade of the 50s and worsens as we age, especially for those who don't exercise. I want to be self-sufficient and independent as long as I can, so I do things like lifting heaving things, pushing myself physically on a regular basis and eating healthy.

But what about maintaining mental health as I grow older? How do I not only make myself harder to kill physically, but mentally? I don’t want to be the ripped-up 85-year-old in the nursing home that doesn’t know where he is!

Until recently, there wasn’t much research that had explored the association between specific dietary patterns and the risk of neurological disorders. However, if you look at research over just the last three years, it suggests that oils widely used in cooking and added to commonly consumed foods, could harm brain cells and heighten the risk of mental decline.

A 2020 study in mice showed that consumption of soybean oil leads not only to weight gain, but also to gene dysregulation that could cause higher rates of neurological conditions like autism, Alzheimer’s disease, anxiety, and depression.

Another study found that feeding mice the equivalent of 2 tablespoons of canola oil per day is associated with worsened memory, learning ability and weight gain, along with “considerable neuronal damage” and increased formation of beta-amyloid plaques, the signature of Alzheimer’s disease.

Need more evidence or don’t think mice are relative enough to humans? How about the results of this study on baby pigs that found increasing the amount of calories from vegetable oil from 1.2% daily to 10.7% daily compromised neurodevelopment. Americans now consume nearly twice that amount, and most baby formulas include vegetable oil as one of the first ingredients.

Are monkeys close enough to humans to believe test results? This study changed the diets of a group of 36 monkeys to a Western diet for 27 months. The change is the monkeys was amazing. They became depressed! The percent time spent depressed was positively correlated with higher concentrations of monounsaturated fats, a higher polyunsaturated fatty acid (PUFA) ratio and higher concentrations of omega-6 PUFAs. Omega-6 fatty acids can be found in sunflower, safflower, soy, sesame, and corn oils.

Vegetable oils, while nearly nonexistent a hundred years ago, now account for over 20% of Americans’ calories and have made their way into nearly every packaged food and restaurant meal we eat, like cookies, salad dressing, bread, crackers, chips, candy, vegetable puffs, granola bars, and even nut milks.

Unlike the name, these oils are not made from vegetables. Vegetable oils are oils extracted from seeds.  Specifically, vegetable oils include:

• Canola oil (also known as rapeseed oil – lovely name)
• Sunflower oil
• Safflower oil
• Grapeseed oil
• Soybean oil
• Cottonseed oil
• Sesame oil
• Corn oil

While some of these seeds in their whole food form are healthy, it’s the crazy amount of processing that must take place to extract oil from the seeds that results in a product that contains unnaturally high levels of polyunsaturated fatty acids (PUFAs), which are highly unstable and prone to further oxidation when heated. 

So what can I (and you) do to protect ourselves from these “brain killers”? I’ve been looking for these dangerous oils for years now. Ever ssince reading Cate Shanahan’s book Deep Nutrition. Despite my efforts, it’s nearly impossible to completely avoid these oils, but there are some things that I do.

Read food labels carefully.  While most foods found in a box or package contain vegetable oils, not all do. I’ve found crackers, chips and even some bars that are free from them.

Don’t cook with vegetable oils.  When it comes to cooking, stick with extra virgin olive oil, coconut oil, or avocado oil. You can get them in spray form, which is helpful as well.

Eat at home or try making your favorite packaged foods at home. This takes some time and lots of trial and error, but there are lots of helpful links online now to recipes.

Don’t feel like it’s not worth the effort. I promise that there is not a single person suffering from a neurological disorder that wouldn’t give anything to go back in time and at least try everything they could to prevent it.