(This post is also a podcast episode! Listen here.)
A few weeks ago I sent a newsletter to the meal mentor community titled, “Are frozen vegetables unhealthy?” For convenience, I’ve posted the newsletter on the meal mentor blog and you can catch a direct link from the show notes on www.getmealplans.com
But I’ll recap quickly right now and end the suspense: Fresh vegetables aren’t so fresh.
It takes 7 to 16 days to transport “fresh” produce (which doesn’t exactly scream “fresh”) and to ensure the food isn’t rotten by the time it gets to the store, produce also has to be harvested prematurely.
(Side bar: If there’s anything I hope to convey with this podcast it’s that we can’t outsmart or cheat nature without consequences)
Back to my point: It takes 7 to 16 days to transport “fresh” vegetables, which requires premature harvesting. Compare this to frozen fruits and vegetables which are harvested ONLY at their peak AND frozen within a few hours.
The freezing aspect is important here because it creates a time capsule. A leaky one, but the taste and nutrition value of frozen produce is mostly preserved while “fresh” produce degrades constantly (losing their important vitamins and nutrients as the clock ticks ticks ticks).
A 2010 study by the Institute for Food Research concluded that fresh produce loses up to 45% of their essential nutrients from farm to table.
(For a list of the top 11 best frozen fruits and vegetables to buy, check out the blog post I mentioned earlier on www.getmealplans.com.)
Now, I know what you’re thinking (because I was thinking this too) “What if I buy from the Farmer’s Market or a farm stand? Or grow it in my own backyard?” Yes, those items would have degraded less and might be more nutritious than frozen.
So haven’t I then just admitted that raw foods are nutritionally superior? Not quite.
In episode 2 “Should you track your calories?” I discussed briefly how every calorie is not ABSORBED the same way.
That by cooking or processing our food, we are better able to absorb the nutrients (and also the calories) in that food.
We’ll get to the energy theory of cooking and how cooking our food made us evolve into homo sapiens in a future episode but for now
Let’s begin with this fun fact:
Humans are the only animals that cook their foods.
Indeed societies all around the world past and present practice cooking, it is one of the few human universals.
In “Catching Fire: How Cooking With Fire Made us Human” Richard Wrangham hypothesized, “Are humans an ordinary animal that enjoys the taste and security of cooked foods or have we evolved to depend on them?”
Raw-foodists claim plants contain “living” or “active” enzymes, which, if eaten raw, operate for our benefit inside our bodies. As such, food cannot be cooked above a certain temperature (45C (113F)) because doing so destroys the “life force” of the enzyme.
I have to quote Wrangham here, “To scientists the idea that food enzymes contribute to digestion or cellular function in our bodies is nonsense because these molecules themselves are digested in our stomach and small intestines. Even if a food enzyme survived our digestive systems, their own specific metabolic functions are too specialized to allow them to do anything useful in our bodies.”
In case you fell asleep, the whole idea of “living foods” is NOT accepted by physiologists.
Reviewing countless real-world studies and volumes of books by anthropologists, some dating back to the early 1900s, Wrangham found “home cooking was the norm and eating raw was a poor alternative demanded by circumstance.”
This was true even for hunter and gatherer populations, including the Inuit (Eskimos). They too cooked their food and preferred it that way. This is remarkable considering they had no bark or branches to make fire most of the year, and had to use animal fat as a burning oil to slow cook their food all day. (They also ate deer poop, which I just have to throw in here for paleo readers).
Wrangham was unable to find any report of people living long term on a raw wild food diet, but he did provide a generous anthology of groups of people who were forced to endure an all raw wild diet, whether it was purely plants, purely raw meat, or a combination of meat and plants.
I was particularly captivated by the Robertson family who survived for 38 days in a dingy after a whale sunk their ship in 1972. The family survived eating mostly raw fish and turtles and doing some funky stuff with makeshift enemas to avoid dehydration.
Anyway, each story suggested that raw diets do not provide enough energy, even when there is no shortage of food available. These people simply couldn’t extract enough of the nutrients or calories from raw foods.
This was even true with the shipwrecked Robertson’s. They caught more food than they could eat, and despite being given more bone marrow than everyone else, Neil Robertson was disturbingly thin when he was rescued.
The Robertson’s were also constantly starving which was my experience on a raw food diet.
I WAS ALWAYS HUNGRY.
Even when I ate more calories than I biologically needed, I was not satisfied. I lived in a state of feeling hungry even when my stomach was uncomfortably full.
The Robertson’s said they fantasized about cooked foods constantly and I remember Zamperini reporting similarly in the book Unbroken.
Not that I’m comparing a juice fast to what the Roberson’s or Zamperini went through, but when I tried to juice fast I became obsessed with pizza. I couldn’t stop thinking about it which seemed odd to me because I don’t particularly like pizza, and in all the times I’d tried dieting in the past, even crazy diets, I didn’t have obsessive food thoughts or cravings quite like that.
Anyway, Wrangham explains “the raw diet supported survival but it also brought out a sense of starvation.” He also said the lack of evidence for longer-term survival on raw wild food suggests that even in extremes, people need their food cooked.”
I mentioned in a previous episode that any given food has a set bioavailability. That is, how many calories, minerals, or vitamins it offers, but that even in the best conditions, we may not absorb all that is being offered. That’s what Wrangham is getting at here.
That’s the energy theory of cooking, which I’ll discuss more deeply in the next episode.
For now, the summation is that by cooking our food, we are better able to absorb the nutrients (and also the calories) in that food.
Admittedly, when I first started learning about this, I thought it sounded a lot like “negative calories.” This idea that a food requires more energy to be digested than the food itself provides. (Here’s the fancy scientific lingo: the thermic effect or specific dynamic action—the caloric "cost" of digesting the food—would be greater than its food energy content.)
There is no scientific evidence to support “negative calories” but there IS evidence that we are unable to absorb the nutrients (and also the calories) in that food, which I’ll talk about more about next time.
To wrap up for now, Wrangham, and a recent study out of Germany, unanimously concluded “a strict raw food diet cannot guarantee adequate energy supply.”
Which I interpret as, even if raw food was magically more nutritious (and this episode definitely poked a lot of holes in that) we humans can’t assimilate enough from it anyway and are thus setting ourselves up for hunger, misery, energy depletion and nutrient deficiency.
It’s sort of like like eating tree bark or cardboard, but maybe small amounts of whole raw foods, such as salads with cooked meals, can help ease the pain of dieting and weight-loss by providing more physical and visual volume without disturbing the needed caloric deficit since we won’t assimilate it. (I need to think more on this).
True for all: cooked food is easier to digest than raw, and all animals grow better on a cooked diet, just ask any farmer.
Wrangham suggests this is why domestic pets become fat--the calories in processed pellets are so much more easily absorbed. It’s similar to my orange vs. Dorito example in the last episode.
Meaning, you might not absorb every calorie in an apple, but you’re probably going to absorb every calorie in an Oreo. The theory of cooking really is amazing…
Let’s circle back quickly to Wrangham’s original hypothesis: “Are humans an ordinary animal that enjoys the taste and security of cooked foods or have we evolved to depend on them?”
Humans, unlike all other animals, have adapted to cooked foods. The reduced size of our digestive system (compared to our ape cousins, for example) limits our effectiveness at digesting raw food.
HOWEVER, that shortened digestive system enables us to process cooked foods with exceptional proficiency. GREAT news from an evolutionary standpoint as I’ll explain in the next episode but not-so-good news when we consider what that means for processed foods and the obesity epidemic.
Finally, and this point is more for my non-vegans listeners, but applies to plants as well: let’s not forget that cooking also reduces the risk of eating toxins or pathogens that make us sick and can kill humans.
Animals do not have these same constraints. They’ll eat roadkill covered in maggots.
Animals don’t worry about salmonella or “starve” on a raw diet. This distinction lead Wrangham, and eventually me too, and hopefully now you as well, that humans need cooked foods.
To be clear, Wrangham doesn’t say it’s IMPOSSIBLE to live on raw foods, but that today’s voluntary raw foodists can only thrive in rich modern environments where they depend on eating exceptionally high-quality foods they do not forage for themselves, and that are also elaborately prepared with special equipment to increase their energy value and absorption.
Which is his very British way of saying “they’re cheating.”
By the way, there’s still one more compelling reason to eat frozen fruits and vegetables (which are lightly cooked)...Did you forget we started out talking about frozen vegetables, the nutrition superstars they are?
Frozen produce is often cheaper, but it also consumes less resources.
The Natural Resource Defense Council released a report stating 40 percent of food in the United States today goes uneaten. This means that Americans are throwing out the equivalent of $165 billion each year AND that all this uneaten food ends up rotting in landfills as the single largest component of U.S. municipal solid waste.
Getting food from the farm to our fork also eats up 10 percent of the total U.S. energy budget, uses 50 percent of U.S. land, and swallows 80 percent of all freshwater consumed in the United States.
Those numbers are quite literally hard to swallow when you realize almost HALF goes to rot in a landfill.
NRDC notes that reducing food losses by just 15 percent would be enough food to feed more than 25 million Americans every year. Increasing the efficiency of our food system is a triple bottom-line solution and buying frozen, meal planning, and using all the foods you buy without having leftovers or waste (which we do with the meal plans) is the easiest way you can help get us there.
There’s a link to the full NRDC report on www.getmealplans.com
If you’re enjoying this podcast, please leave a review on iTunes or share this podcast with your friends.
And speaking of friends, I’d like to give a shoutout to @UglyFruitandVeg on Twitter and Instagram. You should definitely follow them and I commend them for their ongoing efforts in getting all of us to buy food because it’s edible and not worry about if it looks pretty.
Download your free 7-day meal plan at https://www.getmealplans.com.