Hello hello and welcome back to another week of SCIENCE (insert clapping and cheers here). Today I am going to be talking about CARBS.
So I am super excited because one of the studies I am going to summarize in this post was literally published four days ago and was actually a headliner in the Toronto news! The other study I am going to talk about is also fairly recent (2017)…and I’m not sure why it hasn’t gotten more hype.
We live in a word where carbs are seen as the enemy. Currently, low carb diets and even no carb diets have been surging in popularity. But why? We grew up learning repeatedly about the Canadian food guide which suggested most of the food we eat should be carbs. So what is right?
Are carbs the enemy?
First comes first, we need to define carbs. Carbohydrates are a group of chemical substances including sugars, glycogen, starches, dextrins, and cellulose. They comprise the body’s main source of raw material for energy. Other macronutrients are protein (I previously wrote a blog post on how much protein you need HERE) and fats. Protein and carbs are 4 calories per gram while fats are 9 calories per gram.
Now let’s be clear – all carbs are not equal just like all proteins are not equal and all fats are not equal. There’s a difference between oatmeal compared to cake, or chicken breast compared to ribs, or avocado compared to butter. Carbs can be scored based on their glycemic index which is the body’s blood sugar response to eating certain carbs (i.e. sugars). The higher the glycemic index, the larger the glycemic response. The lower the glycemic index, the lower the response and more stable your blood sugar remains.
- Carbs with a high glycemic index: table sugar (aka desserts), white bread,
watermelon, white potato. The spike can increased appetite and sugar cravings.
- Carbs with an average/low glycemic index: oatmeal, sweet potatoes, brown rice, apples, all-bran, bananas, yogurt, chickpeas/lentils
There is a time and a place for simple carbs with a high glycemic index (like breakfast, during exercise, or right after exercise) but most of your carbs should come from complex carbs or lower glycemic index carbs. Fiber is also a carb – this is a carb that cannot be digested but helps you feel full and helps your digestive system function properly.
- Food high in fiber include oats, bananas, apples, peas/beans/lentils
But guess what? Carbs hold on to water. 1g of carb holds on to 3g of water. So the more carbs you eat, the more water you retain. And guess what?!?! Water contributes to weight. SO GUESS WHAT when you eat carbs, you weigh more… but not because of fat but because of water. That is why when you go out to dinner or on vacation you come back with a number way higher on the scale but after a couple days of eating normally again, it goes down. This also contributes to the reason why individuals who go on low/no carb diets, see 5-10lbs of weight loss within the first couple days – They are losing water weight.
Carbs are also the primary source of fuel for our bodies and our brains (but yes, if you don’t eat carbs your body can and will break down fats and proteins to convert to fuel/energy).
The World Health Organization suggests less than 30% of daily intake comes from fats and less than 10% from simple sugars. Health Canada recommends adults eat 45-65% carbs, 15-35% protein, and 20-35% fats. The International Sports Sciences Association recommend athletes eat carbs at every meal to keep a steady state of energy in the body and muscles and eat more carbs before and after working out to increase and replace energy (and sometimes during). They recommend a 1-2-3 rule of thumb of eating 1 part fat, 2 parts protein, and 3 parts carbs for most people who are weight training and exercising to lose weight. They recommend anywhere between 15 and 25% fat, 15-30% protein, and 55-60% carbs depending on the type of athlete. So are all these big wigs wrong?
Now time for the NEW SCIENCE. What did the articles I mentioned at the beginning of this blog have to say?
DO CARBS = DEATH?
The study that came out 4 days ago is called: Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis
They followed about 15,500 US adults for about 25 years…can we take a moment and ooo and aaaa at those numbers? 15 thousand peeps for 25 years! OOOO, AAAAA. okay I’m done… They grouped people into categories depending on how much of their average daily calories came from carbs. The groups were: >65%, 55–65%, 50–55%, 40–50%, 30–40%, and <30% of daily intake coming from carbs. Remember, the ISSA and Canada’s food guide and the World Health Organization recommend about 50%.
And guess what they found? Look at this cool graph:
What does this mean? After considering a bunch of things that are related to dying (like age, sex, race, total caloric intake, diabetes, cigarette smoking, physical activity, income level, and education) the peeps eating about 50–55% energy from carbohydrate had the lowest risk of dying. The peeps eating <40% carbs or >70% carbs had a higher likelihood of dying and died sooner than the peeps eating about 50%.
You might be thinking, okay Jill, don’t get carried away this is one study in one country. First off, did you read 15,500 PEOPLE FOR 25 YEARS?!?!?!? But yes.. okay I get it. It is still just one study. The authors of this study were clever and guessed people would say this so they ALSO combined all the studies done before their study (aka they did a systematic review and meta-analysis… I’ve talked about these studies in different posts. They are real good studies) that followed people for at least 1 year. The studies they found were from North America, Europe, Asia, and other multinational studies.
GUESS WHAT THEY FOUND? After combing all these other studies together to form one big study, they found the peeps who were either low carb or really high carb were more likely to die than the people who ate moderate carb.
One of these other studies collected info on carbs similar to the 15,500 peeps over 25 years study. So only this one other study could make a fancy graph like the one above…BUT GUESS WHAT? It looks almost identical. In the graph below, the red is the study I showed you above (the 15,500 peeps for 25 years) and the blue is a different study. The blue study is on about 135,000 people from 18 countries followed for about 7 and a half years (OOOOOOOOOOOOOOO….AAAAAAAAAAAAAA).
HOWEVER, they also looked at what kind of foods people were eating if they were not eating carbs. They looked at people who replaced carbs with animal-based fats and proteins and people who replaced carbs with plant based fats and proteins. They found the animal peeps were more likely to die and the plant peeps were less likely to die.
That being said, here’s what some smart peeps had to say about the blue (PURE) study:
CARBS DO NOT = DEATH. Eating a moderate amount of carbs is totally fine. If you do go low carb, replace your carbs with plant sources of proteins and fats….but the quality of nutrition science is tricky.
“But Jill, I don’t care about dying, I care about body-fat.”
I get it. Dying is (hopefully) a long ways a way. So how is eating high or low carbs going to impact you right now?
So now let us look at the next study called: Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition
They found 32 studies with 563 people. Carb intake ranged from 1%–83% and fat intake ranged from 4%–84% of total calories.
Figure A shows people with low fat diets expended more daily calories than people with low carb diets (the little grey diamond at the bottom that is on the “favours low fat” side). But the line at 0 represents no significant difference between low fat and low carb. That little grey diamond is SUPER close to 0….. so really…low fat versus low carb didn’t make a difference.
Figure B shows people with low fat diets had lower body fat than people with low carb diets (the little grey diamond at the bottom that is on the “favours low fat” side). But again that little grey diamond is SUPER close to 0….. so really…low fat versus low carb didn’t make a difference.
aka “a calorie is a calorie”
SO THERE IT IS
End of the day, carbs won’t kill you and eating carbs won’t make you fat. I am not saying that low carb or ketogenic diets are ineffective – I am just saying, it really doesn’t matter that much what approach you take as long as you can stay consistent and reduce your overall caloric intake.
These studies were also based on the general population and, as most of you know, nutrition is very individualized (based on preferences, pre-existing health conditions, food intolerances and how your body responds to certain foods). Nutrition Science is also super complex and has many challenges as it is super hard to control and monitor what people eat and all the other risk of factors for obesity and dying! So do I think these studies are the be all end all? No. Is it some of the best evidence we have today? Yes.
So – for most people, eating 50% of your daily calories from carbs will be effective and beneficial in the short and long term. Try to eat more complex carbs than simple carbs. If you are eating carbs high in simple sugars with a high glycemic index, you are going to be hungrier and crave more sugar and food. But if you eat more complex carbs, you’ll have a more stable blood sugar and less cravings. BUT if you like low carb diets/ketogenic diets, that works too! BUT if you replace your carbs with animal based proteins and fats, it appears you may be doing more harm than benefit to your body in the long run. Try to replace your carbs with plant based proteins and fats.
Find what you like and what works for you and stay consistent!
Sending positive vibes and virtual hugs,
The Fitnerd – Jillian
P.S. Check out the photos from the body-positivity shoot HERE!