Paleo Diet, good or bad?
What's your take
A lot of athletes are talking about the Paleolithic diet. What's the best advice for those who want to take their diet back in time?
By Michelle Rockwell, Alexandra Black, & Lindsey Mazanec
Michelle Rockwell, MS, RD, CSSD, is a Sports and Wellness Dietitian based in Raleigh-Durham, N.C. She can be reached through the RK Team Nutrition Web site at: www.rkteamnutrition.com. Alexandra Black, MPH, RD, is the Health Promotion Manager at the International Health, Racquet & Sportsclub Association and provides sports nutrition consultation services to high school and collegiate athletes in Boston. Lindsey Mazanec, MS, RD, is a Weight Management Dietitian at the Children's Medical Center of Dallas.
Athletes are often looking for the perfect nutrition plan. They want a diet that will enhance their athletic performance, support recovery, keep them at a healthy weight, and prevent disease. Some say it is possible to do all of these things through an idea that has been grabbing headlines recently: The Paleolithic diet.
Often referred to as the Caveman diet, the Paleo diet includes only foods that humans consumed during the Paleolithic era (2.5 million years ago until about 10,000 years ago). Obviously there were no Pop-Tarts or cheese curls in the Stone Age, but according to many researchers there were also no beans, grains, or dairy products. "Going Paleo" is based on the premise that our bodies are designed to eat what our ancestors did and not the current American diet.
Some researchers, diet proponents, and athletes themselves have reported significant health, weight control, and performance benefits related to following the Paleo diet. But there is little research to back its effectiveness, especially for athletes in team sports, and it is very different from what most sports dietitians recommend to athletes today.
When an athlete tells you he or she wants to go Paleo, how should you respond? In this article, we describe the Paleo diet, its reported benefits, potential challenges and concerns, and how athletes may be able to adopt various Paleo principles that can work to their advantage.
Attention from professional athletes and mainstream media outlets, along with plenty of Internet sites, blogs, and magazine articles has made Paleo eating a familiar trend throughout the country. The recent widespread popularity of the diet can be attributed in large part to Loren Cordain, PhD, a professor and researcher from Colorado State University who began publishing studies on the physiological effects of Paleolithic nutrition more than 30 years ago.
Cordain's work was published as early as the mid-1970s in the New England Journal of Medicine. He has also written several books on the topic, including The Paleo Diet and The Paleo Diet for Athletes (which he co-authored with endurance coach Joe Friel). Both books have experienced booming sales, particularly in the last three years.
In his research, Cordain claims that the Paleo diet is how our bodies were genetically designed to eat. He says that natural foods are the only foods needed for basic body functioning. Dairy, grains, and unnatural, processed foods that didn't come along until humans invented them carry more negative health risks than positive ones like saving time and ease of preparation.
In a nutshell, Paleo foods include:
- Lean meats (especially grass-fed animals) like chicken, turkey, pork, lean beef, and buffalo
- Fish and seafood
- Fresh fruits
Non-starchy vegetables (broccoli, salad greens, bell peppers, carrots, and squash)
- Nuts (except peanuts) and seeds
- Plant- and nut-based oils (olive, walnut, grapeseed, and coconut).
Foods that are not part of the Paleo diet include:
- Grains (oats, wheat, and barley)
- Starchy vegetables such as potatoes
- Dairy (milk, yogurt, cheese, etc.)
- Legumes and beans
- High-fat meats (salami, bacon, sausage, hot dogs, regular hamburger meat, and high-fat cuts of steak)
- Processed foods and trans fats
- Salty foods.
The Paleo diet does not recommend specific amounts of foods or portion sizes, but its meals are generally higher in protein than the typical American diet. It contains a greater percentage of calories from carbohydrates than is prescribed in popular low-carb diets, but less than the amount of carbohydrates commonly recommended by health and nutrition professionals.
While the Paleo diet has gained in popularity among the general population during the past few years, it has also caught the attention of many athletes in a variety of sports. Triathletes and other endurance athletes, weight lifters, and other strength/power athletes are particularly interested.
For example, the Paleo diet has become synonymous with CrossFit training, a strength and conditioning program described as "constantly varied, high-intensity, functional movement." Athletes use a combination of basic exercise equipment such as dumbbells, medicine balls, and plyometric boxes along with less common workout objects like ropes, chains, and tires to train in very rigorous sessions that typically last one hour. CrossFit focuses on returning to natural, functional movement training. This idea of a more naturally inspired workout coincides with the Paleo diet's focus on natural, unprocessed foods.
Athletes on the Paleo diet are advised to follow typical Paleo guidelines for their day-to-day eating, but add necessary nutrients before, during, and after workouts. Cordain's The Paleo Diet for Athletes recommends the following:
Before exercise: At least two hours before exercise, the book suggests that athletes consume low glycemic index, low fiber carbohydrates and protein, plus fluids. Closer to the start of a workout, higher glycemic, more liquid carbohydrates are permitted.
Suggested pre-exercise foods include eggs and fruit (but not apples, berries, dates, figs, grapes, pears, mangoes, or pineapples), applesauce mixed with protein powder, jarred baby food such as fruits or veggies mixed with chopped meats like turkey, fish, or chicken, and liquid meals. Common pre-exercise starches such as wheat toast or oatmeal are not recommended.
During exercise: Per hour of exercise, Cordain's book says athletes should consume 60 grams of easy-to-digest higher glycemic index carbohydrates. Sports drinks are suggested to meet this goal.
After exercise: Within 30 minutes of exercise completion, carbohydrates are recommended to replenish muscle glycogen. Protein to repair muscles, fluids and electrolytes to rehydrate, and fruits and veggies to reduce acidity of body fluids are also necessary. Non-Paleo starches and sugars are allowed at this time. Ninety minutes after exercise completion, the athlete is instructed to repeat this regimen. (The amount of total carbohydrate consumed is based on body weight and exercise duration.) Examples include a recovery drink containing protein and carbohydrate and a banana, or a sports drink, slice of bread with turkey, tomatoes, and spinach, and melon.
There are quite a few positives that can be attributed to following the Paleo diet. Because natural foods are the basis of the diet, it may be best for what it excludes. Fewer additives, preservatives, and chemicals that can be harmful or problematic are consumed. "Whether you call it Paleo or some other flashy name, eating whole foods or 'eating clean' can have numerous benefits to athletes," says Cheryl Zonkowski, MS, RD, CSSD, Performance Dietitian for Navy Special Warfare.
We also know that many Americans, including some athletes, overeat carbohydrates and fats. By limiting carbohydrate options to exclusively fruits and vegetables--no refined flours or sugars--it is unlikely athletes will overload on carbs. And because in addition to trans fats, higher fat or heavily processed meats are avoided, the Paleo diet is reasonably low in saturated fat.
Rich consumption of unsaturated fats, coupled with a high fruit and vegetable intake, can help athletes by reducing inflammation. Because Paleo carbohydrates are derived almost exclusively from fruits and non-starchy vegetables, fiber, vitamin, mineral, antioxidant, and phytonutrient consumption can be quite high. The diet also limits alcohol consumption to less than one serving of wine per day.
Another potential positive involves the notion that dietary acid/base balance can greatly impact homeostasis and health. Cordain says that when high acid foods like cheese, grains, and lentils are consumed in excess, the body must buffer the acidic load with an alkaline base. If there is not enough base present in the body, bone and muscle may be broken down in order to help the neutralization process. Because most fruits and vegetables have a high alkaline content and are a staple of the Paleo diet, it is thought that Paleo eating can help maintain desired acidity levels better than the current American diet can.
We also know that many athletes encounter iron deficiency, which is less common with the high meat consumption component of the Paleo diet. Some athletes may have concerns about increasing portions of meat in their diets, specifically beef since it is perceived as high fat or otherwise unhealthy. But according to Michael Roussell, PhD, author of The 6 Pillars of Nutrition and lead researcher of the BOLD (Beef in an Optimal Lean Diet) study, this is nothing to worry about.
"The latest evidence demonstrates that lean beef--including popular cuts like top sirloin steak, T-bone steak, and 95-percent lean ground beef--can be part of an overall heart healthy, nutrient-rich eating plan that can improve cholesterol levels," he says. "Many athletes can benefit from adding high-quality lean protein to their diet. On average, a three-ounce serving of lean beef provides 10 essential nutrients, including 25 grams of protein and only about 150 calories."
Several research studies have shown that a Paleolithic diet can also help improve markers of health in both healthy people and those with chronic disease. One study comparing the Mediterranean diet (rich in grains, other plants, fruits, vegetables, nuts, oils, and fish, with minimal animal products) and Paleolithic diet in people with heart disease and either glucose intolerance or type 2 diabetes showed that those following the Paleo diet saw greater improvements in blood sugar control.
Another study showed that a Paleolithic diet resulted in lower mean glycated hemoglobin values, diastolic blood pressure, and waist circumference, and higher HDL cholesterol levels among participants when compared to a standard diet for diabetes patients. Among healthy adults, a small metabolically controlled study found improvements in blood pressure, glucose tolerance, insulin sensitivity, and cholesterol profiles without weight loss over a 10-day period.
Finally, though there aren't any published research studies supporting weight loss in athletes who follow the Paleo diet, there is evidence of weight control benefits among the general population. The high-protein, low-carbohydrate requirements of the diet have demonstrated to be effective for fat loss in a number of studies. And a recent study appearing in Nutrition & Metabolism found that Paleo dieters not only felt more satisfied in terms of appetite, but also had lower levels of circulating leptin, a hormone that regulates appetite, food consumption, and body fat storage.
On the other hand, there are some concerns with following the Paleo diet. To start, some question the premise. Haven't our bodies adapted physiologically over time to the way we've been feeding them? It's also important to point out that our health as a society declined recently--in the past 25 years--not 10,000 years ago when humans started eating gluten, grains, beans, dairy, and sugars. Cordain is certainly correct that the introduction of trans fats and high fructose corn syrup is to blame for some of our society's current health problems, but there are several other problems to blame as well, including sedentary lifestyles and out-of-control portion sizes.
Another problem with going Paleo is that processed foods dietitians often recommend, such as fortified whole grain cereals, are not allowed. Though we consider legumes, brown rice, and sweet potatoes high-quality carbohydrates, they are not part of the Paleo diet either. And all dairy products are disallowed because they are modernly produced foods.
"The emphasis on a pre-agricultural diet can encourage more consumption of nutrient-dense, unprocessed foods and reduce consumption of foods with substantial added sugar and salt," says Janet Rankin, PhD, President of the American College of Sports Medicine. "However, the elimination of grains, dairy, and legumes can make it more difficult to consume appropriate amounts of nutrients such as calcium, carbohydrates, and dietary fiber, thus making it more challenging to consume a diet that is optimal for athletes."
Some who begin a Paleo eating pattern remove carbohydrates, grains, and dairy from their diet but don't replace the nutrients they've been getting from these foods with other food substitutes. When an entire food group--or close to it--is missing from an athlete's diet, there is potential for problems.
"Any diet that overly restricts the intake of one or more food groups runs a real risk of falling short on vital nutrients," says Enette Larson Meyer, PhD, RD, Chair of SCAN (Sports, Cardiovascular, and Wellness Nutrition). "Those who closely follow the Paleo diet and severely restrict or eliminate dairy products and grains may not be consuming sufficient amounts of calcium, potassium, selected B vitamins, and fiber."
A highly criticized aspect of the Paleo diet is its low carbohydrate content, which can have detrimental effects on exercise performance and recovery. Although followers are advised to take in non-Paleo carbohydrates (starches and sugars) before, during, and after exercise, they are supposed to avoid all sources of carbohydrates other than fruits and non-starchy vegetables in their general training diets. This may mean an inadequate supply of carbohydrates through fruits and vegetables, which could lead to depletion of glycogen stores and low energy levels.
Although it's true that many Americans, and even many exercisers and athletes, over-consume carbohydrates, most sports dietitians agree that competitive athletes need between five and 10 grams of carbohydrate per kilogram of body weight per day, with endurance and ultra-endurance athletes sitting at the higher end of that recommendation.
This means that the average 140-pound female athlete would need between 320 and 636 grams per day. To eat the minimum amount using only Paleo-approved foods, she would need to consume the following fruits and vegetables throughout the day: two bananas, one apple, three cups of broccoli, one avocado, two cups of butternut squash, two cups of grapes, two cups of kale, a quarter-cup of raisins, two cups of cooked carrots, and two cups of zucchini and yellow squash. This isn't easily achievable for most people on a daily basis.
Since dairy, a major source of calcium in the U.S., is eliminated when following the Paleo diet, an athlete may put themselves at risk for stress fractures. According to a review published in the March issue of the European Journal of Clinical Nutrition, high protein diets do not lead to bone calcium loss, except in the absence of adequate calcium supply.
The acid load of a higher protein intake without enough calcium can result in calcium leached from the bone if not buffered by adequate intake of foods that contain potassium. In theory, athletes on the Paleo diet would eat enough potassium-rich foods like bananas, peaches, tomatoes, and greens that the lack of calcium intake would not be a problem, but it would need to be a daily focus so as not to put their body at risk.
In addition, according to Cordain, the hunter-gatherer societies he references were moderately active throughout the day, and it has been proven that being active throughout the day helps with calcium retention. This is not the case for many Americans. Even athletes in training, while very active during workouts and practice, may be sedentary at school, while studying, and on off-days, which can impact calcium retention.
Finally, the logistics of eating Paleo can be tough. US News & World Report ranked the Paleo diet second in its list of diets that are hard to follow. Though a lot of Paleo recipes are user-friendly because fewer ingredients are called for, they do require planning ahead, which can be difficult for a college athlete who is constantly on the go. Athletes traveling for competition also face challenges with such a limited food repertoire. And Paleo eating at a college training table or even in the dining hall can be challenging since pasta, rice, bagels and other bread products, dairy, and processed foods often make up a significant portion of the options.
Furthermore, some Paleo foods can be expensive, especially if an athlete wants to follow the diet so closely that they purchase only organic foods and grass-fed animal meats. A common stumbling block with Paleo eating is to fall into the trap of skimping on lean meats due to cost and therefore eating a lot of higher-fat meats like bacon and lower-priced cuts of steak.
The Paleo diet is designed to be a lifestyle change that is followed permanently. Younger athletes especially may not stick with it on a long-term basis. Paleo recommends breakfasts such as poached salmon or grilled chicken, which would be a huge change for many athletes. Remember the jarred baby food suggestion? Not many athletes find the idea of eating baby food before a workout very appealing.
The psychological ramifications of such extreme eating is also concerning to many sports nutrition professionals. The strict nature of the diet, specifically omitting so many foods and food categories, can set athletes up for feelings of guilt any time they deviate from the diet plan. Guilt about "cheating" can set up a cycle of restricting and binging that can lead to poor diet adherence and even disordered eating patterns. A more balanced approach to nutritional modification is almost always more sustainable and mentally healthy.
If an athlete is considering the Paleo diet, we suggest that they ask themselves the following questions before diving in. We also offer some suggestions on ways to modify the diet for athletes so that they are still fueling for optimum performance.
Why are you considering the Paleo diet? If it's because you aspire to eat more natural, unprocessed foods, that's great. Many athletes can benefit from that change. If it's for a specific weight modification, health, or performance goal, work with a sports dietitian to establish guidelines best for you.
How different is Paleo from your current way of eating? Subtle and gradual nutrition changes are often more sustainable than drastic diet overhauls. Write out a few days' worth of meals you would eat on the Paleo diet and evaluate if they are realistic for you. It might be easier to implement any changes piecemeal and not just jump into Paleo-only eating full-time right away.
Will Paleo eating affect your training? If you periodize your training, you have changing nutritional needs throughout a training cycle and during the season and off-season. There may be times when Paleo eating is more suitable and times when it is not. For example, carbohydrate needs are higher during more intense training. Sometimes athletes learn great things about their diets through trial and error, but be sure it's an appropriate time for experimentation.
Will you get enough carbohydrates? It is important that you follow the Paleo advice to emphasize carbohydrates before, during, and after every training session, workout, and competition. For some athletes, that may be enough carbohydrates, but for others it may not, which can set you up for early fatigue, soreness, and potential injury and/or illness. Be sure to include plenty of fresh fruits as they are a natural source of carbohydrates.
Will you get enough calcium? If you are unwilling to consume dairy, it is still possible to meet the recommended daily allowance (RDA) of 1,200 milligrams of calcium, but it will be more difficult. Alternate food sources include almond milk, which contains 30 percent of the RDA per eight-ounce glass; spinach, which provides about 10 percent of the RDA per half cup; canned fish like sardines, which provide a little over 25 percent of the RDA per three-ounce serving; and salmon, which provides about 15 percent of the RDA per three-ounce serving. If you cannot meet calcium needs through diet, you should take 1,200 to 1,500 milligrams of calcium citrate or carbonate per day.
Will you get enough vitamin D? Most dairy is fortified with vitamin D, so if you are not consuming dairy, this is a concern. Adequate vitamin D levels contribute to normal calcium metabolism and uptake and have been linked to numerous physical and mental benefits. Some athletes get enough vitamin D from exposure to sunlight while training outdoors, but for those who are indoors for long periods of time or cover up due to cold weather, some good sources of vitamin D include fatty fish, tuna, liver, and eggs. The RDA for vitamin D can be met by eating just three ounces of swordfish or salmon. A vitamin D supplement is also an option. Work with your healthcare provider to ensure your serum hydroxy vitamin D levels are at least 32 ng/L.
Many athletes who eat Paleo either follow the diet most of the time or pick and choose which aspects work for them. One popular modification involves including some dairy. Or some athletes follow an 85/15 rule, in which about 15 percent of the time meals or snacks include "forbidden" items like dairy, peanut butter, hummus, oats/oatmeal, brown rice, sweet potatoes, alcohol, or craved sweets like dark chocolate.
Well-designed scientific research studies showing athlete-specific benefits of the Paleo diet are lacking. However, anecdotal evidence, possible body composition and health benefits, and the popularity of the diet continue to pique athletes' interest.
In the end, when an athlete is considering any type of new nutrition plan, he or she is generally a captive audience prepared to make deliberate change. If an athlete comes to you for advice about the Paleo diet, listen to what they have to say and educate them about its potential positives and negatives. If they want to give it a try, help them figure out the best way to implement any aspects of the diet that will help them continue on a path to optimal performance.
- Alicia M. Fogarty M.S., R.D., L.D.N.
LiveWELL Health Centers for the YMCA's of Greater Charlotte
Carolinas Healthcare System
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