Nutrition Basics: Carbs, Fats, and Protein
Stan Reents, PharmD
05/29/2018 01:52 PM
Last Revision: 12/12/2018 09:10 AM
Let's face it: we don't always eat right.
However, it's not always our fault. Nutrition is a complicated arena. Unless you have formal training in nutrition, you will be susceptible to advertising and marketing pitches. And, the widespread availability of snacks, junk foods, drive-thru fast-food franchises, and other "convenience" foods just makes it too easy to consume unhealthy foods.
That's why we developed this series of articles titled "Nutrition Basics." Here, we'll review carbs, fats, and protein, the 3 major nutrients.
NUTRITION 101: KNOW YOUR CALORIE SOURCES
There are 4 sources of calories in our diet: carbs, fats, protein, and alcohol.
Carbs and fats are your primary energy sources. Even though protein contributes to the total calorie amount of a food or beverage, protein is not really considered a major energy source. And of course, alcohol is not an essential nutrient like the other 3 are, but we need to include it in this discussion because many people overlook alcohol as a significant source of calories in their diet.
Here are the values for those calorie sources. The Atwater values are the precise scientific values. However, slightly different values are used for packaged food labels:
||CALORIES PER GRAM:
|CALORIES PER GRAM:
|Fats & Oils
("kcal/g": kilocalories per gram of food; in conversation, the term "calories" is commonly used instead)
Use glycemic index and glycemic load to guide your carbohydrate choices. These concepts explain how fast your blood glucose rises after consuming different types of carbohydrates. Foods are rated on a 0-100 scale. Glucose itself has a rating of 100. Sucrose, or table sugar, is rated lower. The glycemic index of specific foods can be found at: www.GlycemicIndex.com.
A high glycemic index indicates a food that causes your blood glucose to spike up very rapidly. However, how fast your blood glucose rises after consuming a specific food has nothing to do with how sweet it tastes. For example, white bread and corn flakes have a higher glycemic index than ice cream.
During a prolonged race, tennis match, basketball game, etc., athletes should consume easily-digestible (simple) carbs. Simple carbs, which are generally higher glycemic index, can be burned for energy faster than complex carbs, and much faster than fats can. So, in this scenario, high glycemic index carbs are useful. The best example here is Gatorade®: it contains glucose and fructose, both simple carbs. Simple carbs like this are absorbed quickly from the gut and uptaken easily by skeletal muscles.
But, at all other times, make sure that you focus on consuming complex carbohydrates (example: vegetables). These have a lower glycemic index. A small study from the UK showed that when distance runners consumed a diet of low glycemic index (GI) foods after running, they were able to run longer the following day compared to runners who consumed a diet of high GI foods in between the 2 runs (Stevenson E, et al. 2005).
And there is a ton of research showing that regular consumption of a diet that is too heavy in sugar and other refined carbohydrates (all are high glycemic index foods) contributes to a long list of chronic health problems. Complex carbohydrates are healthier.
Fats are the most complicated of the 3 major nutrients. So, for that reason, there is the potential for confusion.
Whereas starches (long-chain carbohydrates) are broken down into smaller chunks called simple sugars, and, proteins are also broken down into amino acids, fats (specifically, "fatty acids") are incorporated directly into cell membranes and used without being broken down. Thus, fats and oils can have profound effects on our health.
First, note that fats and oils are the same types of nutrients. If the substance is a solid at room temperature, it is called a "fat." If it is a liquid at room temperature, it is referred to as an "oil." On packaged food labels, you'll see specific types of oils listed in the Ingredients list, but where the actual amounts are summarized, you only see "Fats."
Fats and oils fall into 4 categories:
- saturated fats
- mono-unsaturated fats
- poly-unsaturated fats
- trans fats
• Trans Fats: Trans fats are the easiest to discuss and understand. Trans fats arrived on the scene in 1911 when Proctor & Gamble introduced Crisco®, made from partially hydrogenated cottonseed oil. Today, you mainly find trans fats (referred to as "partially hydrogenated ____ oil" on the labels of packaged foods) in processed snack foods, pastries, and fried foods. Avoid them as much as you can: there is no question that trans fats exert detrimental effects on your vascular system. For the most part, food manufacturers are steadily eliminating trans fats from the mix, due to rules requiring this. But fried foods from restaurants still contain trans fats.
• Saturated Fats: In 1968, the American Heart Association's Committee on Nutrition recommended a decreased intake of saturated fats and an increased intake of poly-unsaturated fats (Kritchevsky D. 1998). Ever since then, saturated fats have gotten a bad rap. Replacing butter and lard (both high in saturated fats) with vegetable oils (low in saturated fats and high in poly-unsaturated fats) is commonly believed to be a desirable health strategy. However, not all experts agree that saturated fats are the primary cause of coronary heart disease (Chowdhury R, et al. 2014) (Malhotra A, et al. 2017). The story of these 2 fats is not as simple as saying: saturated fats are universally bad and poly-unsaturated fats are universally good for us. Keep in mind that "saturated fats" (as well as "poly-unsaturated fats") represents a group of molecules, not a single molecule. For example, the saturated fatty acids in dairy products are not as detrimental to LDL-cholesterol levels and heart disease risk as are the saturated fatty acids in meat (Chen M, et al. 2016) (de Oliveira Otto MC, et al. 2012) (Sjogren P, et al. 2004). Unfortunately, the different types of saturated fatty acids (eg., lauric acid, myristic acid, palmitic acid, stearic acid, etc.) are not listed on the labels of any packaged foods. Coconut oil is an example of a plant oil that is high in saturated fat: about 92% of the fat content in coconut oil is saturated fat. For comparison, butter contains 66% saturated fat.
• Mono-unsaturated Fats: Mono-unsaturated fats and poly-unsaturated fats are nearly identical. The main difference is that mono-unsaturated fats have only 1 double-bond in their chemical structure, whereas poly-unsaturated fats have 2 or more. But that very tiny difference in chemical structure can mean substantial differences in how the fat/oil affects our health. Mono-unsaturated fats are found in avocados, olives, olive oil, canola oil, hazelnuts, and macadamias. Generally, these foods are good for us.
• Poly-unsaturated Fats: The combination of a pervasive marketing effort on top of scientific research has elevated poly-unsaturated fats to "preferred" status from a health perspective. You may recall ads claiming "high in poly-unsaturates!" and recommending that we should all cook with vegetable oils. But, newer research is questioning this health endorsement that plant oils that are high in poly-unsaturated fats are universally good for us (Calder PC. 2010) (de Lorgeril M, et al. 2012) (Ramsden CE, et al. 2010) (Ramsden CE, et al. 2011) (Ramsden CE, et al. 2013) (Ramsden CE, et al. 2016). Four plant oils -- safflower oil, sunflower oil, soybean oil, and corn oil -- contain high concentrations of the omega-6 type of poly-unsaturated fatty acid (PUFA). During the 20th century in the US, consumption of these 4 dietary oils -- especially soybean oil -- increased enormously (Blasbalg TL, et al. 2011). One hundred fifty years ago, we consumed a diet that was roughly balanced in the amounts of omega-6 and omega-3 fatty acids. Animals also naturally consume a diet that contains balanced amounts of these 2 fatty acids. However, today, the average American consumes a diet containing an O-6/O-3 ratio around 20:1, and for some people, as high as 30:1. It is now recognized that a steady diet that contains way too much omega-6 PUFA and too little omega-3 PUFA is a recipe for chronic health problems as we get older (Simopoulos AP. 2008). So, the best advice is to reduce your consumption of those 4 plant oils mentioned above and increase your consumption of the omega-3 type of PUFA.
Are you confused yet? The issues with fats and oils can be summarized as "total amount" vs. "types":
• For optimum health: The TYPES of fats and oils you consume is more important than the TOTAL AMOUNT you consume. Most people need to consume less omega-6 poly-unsaturated fats and more omega-3 poly-unsaturated fats. Aim for an O-6/O-3 ratio of no higher than 4:1 (Simopoulos AP. 2008). So, reduce your consumption of foods that contain safflower oil, sunflower oil, soybean oil, and corn oil. But, good luck with that: pretty much all processed foods -- even healthy-sounding products such as nutrition bars -- typically contain 1 of those 4 oils. I recently saw a bag of dried peaches that states it contains sunflower oil! You can increase your consumption of omega-3's by eating fish and walnuts (Marangoni F, et al. 2007). Other good sources of omega-3's are algal oil (ie., from algae, where fish get their omega-3), chia seeds, and flaxseeds.
• To improve your athletic performance: For people who exercise regularly and maintain their aerobic fitness, the TOTAL AMOUNT of fats and oils you consume (ie., the ratio of fats relative to carbs and protein) is more important than the specific TYPE you consume. In other words, a diet that is way too low or way too high in fats is more likely to harm performance than consuming too much of one particular type of fat. Here's an example showing that exercising regularly can offset the potential harms of too much saturated fat: While it's well-known that consuming saturated fats increases the production of LDL-cholesterol, some research shows that a high degree of aerobic fitness can offset the cardiovascular health risks of an elevated LDL (Farrell SW, et al. 2012).
Protein is probably the most misunderstood of the 3 major nutrients. As I mentioned above, protein is not really considered a major energy source.
Consuming enough protein every day is important for other reasons. Dietary protein supplies your body with the essential amino acids that are required to synthesize structural and functional proteins, and, the enzymes that run your complex metabolism. And it's not just athletes who need to maintain a good intake of protein: It is clear that protein intake is critical to the health of all adults, especially older adults (Houston DK, et al. 2017).
Specific Amino Acids
Amino acids are the building blocks of proteins. The table below summarizes the different categories of amino acids:
• isoleucine (BCAA)
• leucine (BCAA)
• valine (BCAA)
• aspartic acid
• glutamic acid
Several important concepts are:
• Essential Amino Acids vs. Non-Essential Amino Acids: "Essential" amino acids are those that must be supplied by foods...ie., the body cannot synthesize these. The "best" sources of dietary protein contain all of the essential amino acids. Animal proteins are slightly better than plant proteins in this regard.
• Branched-Chain Amino Acids (BCAA): Branched-chain amino acids are thought to be better at promoting muscle growth than non-branched chain amino acids. However, consuming individual branched-chain amino acids doesn't always work: in one study, elderly subjects were given leucine for 6 months. No increase in muscle mass or muscle strength was seen (these subjects were not weight-training at the time) (Leenders M, et al. 2011). Whey protein contains BCAA's. A good source of whey protein is milk: its 2 major proteins are caseine and whey.
• Glutamine: Glutamine is the most abundant amino acid in skeletal muscle.
Having said that, the attitude towards animal protein is beginning to take a dramatic shift. Animal protein is now believed to promote tumor growth. Plant protein does not do this...at least, not to the same extent.
Researchers such as Luigi Fontana, MD, PhD, at Washington University in St. Louis, have identified several sub-cellular molecular pathways of cell growth that are stimulated when we consume animal protein (Fontana L, et al. 2015) (Levine ME, et al. 2014). Note that dietary protein from any animal source -- ie., not just meat -- can stimulate these pathways.
Why is this bad for us? The simple explanation goes like this:
Consumption of animal protein stimulates molecules known as growth factors. When we are young, elevated amounts of growth factors are a good thing. This makes sense when you think of wild animals. When a baby gazelle or giraffe or zebra is born, it is walking within minutes. Then, it has to grow up fast, otherwise it will be a meal for predators. These baby mammals mostly consume mother's milk, which is rich in protein...ie., animal protein.
However, after we reach adulthood, we don't need this same degree of cell growth stimulation. A lot of research supports the warning that excessive consumption of meat can increase the risk for cancer and heart disease. One of the earliest reports came from the famous Adventist Health Study in 1992 (Fraser GE, et al. 1992). This is an ongoing evaluation of people living in Loma Linda, California. Today, it is realized that it's not just red meat to be wary of, but, all sources of animal protein: ie., eggs, milk, cheese, etc. New research confirms the findings from the Adventist Health Study, ie., that protein from plant sources is less risky than protein from animal sources for cardiovascular disease (Richter CK, et al. 2015).
But the recommendation to avoid animal protein would seem to contradict long-held sports nutrition beliefs: ie., athletes need more protein than non-athletes, don't they? And, consuming protein immediately after a work-out is a valid sports nutrition strategy. Indeed, chocolate milk has actually been researched and recommended as a great way to "protein load" and recover right after a work-out (Roy BD. 2008).
Animal protein isn't a requirement to perform at high levels. Just look at Ironman triathlete Brendan Brazier: www.BrendanBrazier.com. He's a vegan and has won the Canadian 50-km Ultra Marathon twice.
Perhaps even more impressive is another Ironman triathlete Rich Roll: www.RichRoll.com. He conquered the "EPIC-5": five Ironman triathlons, all completed in less than a week, and each one on a different Hawaiian island! But wait, there's more: He also completed an Ultraman: a triathlon distance of 320 miles over 3 days. Now here's the kicker: he's also a vegan. This is a complete turn-around for him: when he turned 40, he was 50 pounds overweight and unable to climb the stairs without stopping.
So, am I suggesting that athletes should consume plant protein instead of animal protein in all these sports nutrition scenarios? In a word, "yes!" In fact, this now appears to be a very wise recommendation for all adults! See: "The Plantrician Project."
If you think that sounds drastic, consider what Joel Fuhrman, MD, promoter of the plant-based Nutritarian Diet says: "Meat is a disease-producing food."
Yes, it's true. We should stop thinking of the huge steak as the epitome of fine dining. Rather, the lowly bean is rapidly climbing to the top of the "preferred" protein list. Beans are great protein sources.
There are several possible explanations why beans are a healthier protein source than red meat:
• Beans are lower in the amino acid methionine than red meat is. The body metabolizes methionine to homocysteine, which has been regarded as a risk factor for heart disease.
• Beans are low in saturated fat; meat is high in saturated fat.
• Beans are an excellent source of fiber, whereas red meat contains none.
• Beans contain other nutrients not found in meat.
• Beans and red meat are both good sources of iron. But, the iron in red meat is provided as "heme iron." This form of iron has been associated with an increased incidence of diabetes. It is thought that heme-iron can damage the islet cells of the pancreas.
Just a brief comment on alcohol here since it is relevant to the discussion of calories...
Yes, alcohol is a carbohydrate, but, keep in mind that alcohol offers 7 kcal/g compared to other dietary carbohydrates (except for fiber) which offer only 4 kcal/g.
If you'd like to have a novel way of looking up the calories in over 400 types of beers, check out our Exercise Calorie Converter mobile app!
Alcohol will be discussed in depth in another review, but, for now, note that red wines and hoppy beers are good sources of antioxidants: Red wines contain resveratrol, hops contain xanthohumol, and malt contains ferulic acid.
WHAT'S THE RIGHT RATIO OF CARBS, FATS, AND PROTEIN?
Now that we've covered some nutrition basics, a logical question is: "what's the optimum ratio of carbs, protein, and fat in our daily diet?"
During the past decade or so, the importance of "dialing in" the perfect ratio of carbs, fats, and protein has fallen out of favor. Instead, what's really important is to make healthy choices within each of those 3 major categories.
Having said that, what do the latest Dietary Guidelines for Americans say?
The table below summarizes "model" dietary patterns that the committee feels are acceptable (Millen BE, et al. 2016):
"STEPS" YOU SHOULD TAKE
The most important concept is to make smart choices within each of the 3 major nutritional groups every day. Don't worry so much about achieving a precise ratio of carbs, fats, and protein:
Carbohydrates: Simple (high glycemic index) carbs are acceptable during prolonged exercise. However, at all other times, focus on complex carbs...ie., carbs with a lower glycemic index. Consuming a plant-based diet will achieve this.
Fats and Oils: If you have a high LDL-cholesterol, and, certainly if you've had a myocardial infarction or a stroke, then reduce your consumption of saturated fats. Cut back on meat first because meat poses a variety of risks. Increase your consumption of mono-unsaturated fats. Note that poly-unsaturated fats can be either the omega-3 type or the omega-6 type. Most people consume too much omega-6 and too little omega-3. Cut back on foods that contain safflower oil, sunflower oil, soybean oil, and corn oil. One of these 4 oils will be found in nearly every brand of cracker, chip, and cookie. Increase your consumption of omega-3's by consuming more fish, walnuts, chia seeds, flaxseeds. Shoot for an omega-6/omega-3 ratio of no higher than 4:1. Avoid fried foods to minimize your consumption of trans fats.
Protein: Cut back on all sources of animal protein. Strive to obtain protein from beans, nuts, Greek yogurt.
Q: Are the nutritional facts that restaurants and food labels provide accurate?
ANSWER: Regarding the nutritional information provided by restaurants, a report published in the July 20, 2011 issue of JAMA revealed that 19% of menu items studied contained at least 100 calories (kcal) more than what was stated (Urban LE, et al. 2011.) That's not a lot, but, for people who are trying to limit their calories, this could be significant. Don't forget that an excess of 500 kcal per day will lead to a 1-lb weight gain after 7 days.
Labels on packaged foods are generally accurate, but consumers should realize several "rules" that are in play: First, the Total Calories value is always rounded up to the next unit of 10. In other words, if the total calorie amount is 133 calories, then, it would be reported as "140 calories." Second, for some ingredients, if the actual amount is less than 0.5 g, then manufacturers are allowed to report the amount as "zero." A case-in-point is the term "fat free": this phrase can be used if the food contains less than 0.5 g of fat. Note that even a very small amount could add up if, say, you are consuming 10 nutrition bars during a century ride, for example.
Q: What's the best carbs/fats/protein ratio to enhance athletic performance?
ANSWER: This is a very detailed topic. It will be covered in a separate review.
FOR MORE INFORMATION
The federal government publishes "Dietary Guidelines for Americans" every 5 years. The most recent document can be obtained here: 2015-2020 Dietary Guidelines for Americans.
Even though it was originally published in 2008, Dr. John La Puma's book "Chef MD's Big Book of Culinary Medicine" is superb. In addition to being an internist, Dr. La Puma is a professional chef. In this book, he summarizes the foods to avoid and the foods to emphasize for dozens and dozens of specific disease states. Each recommendation is supported with citations to published scientific research which are listed at the end. Honestly, we've never seen any other book like it!
Readers may be interested in these other Articles on diet, nutrition, and sports nutrition:
EXPERT HEALTH and FITNESS COACHING
Stan Reents, PharmD, is available to speak on this and many other exercise-related topics. (Here is a downloadable recording of one of his Health Talks.) He also provides a one-on-one Health Coaching Service. Contact him through the Contact Us page.
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ABOUT THE AUTHOR
Stan Reents, PharmD, is a former healthcare professional. He is a member of the American College of Lifestyle Medicine (ACLM) and a member of the American College of Sports Medicine (ACSM). In the past, he has been certified as a Health Fitness Specialist by ACSM, as a Certified Health Coach by ACE, as a Personal Trainer by ACE, and as a tennis coach by USTA. He is the author of Sport and Exercise Pharmacology (published by Human Kinetics) and has written for Runner's World magazine, Senior Softball USA, Training and Conditioning and other fitness publications.
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