Going Keto: Does the Ketogenic Diet Improve Athletic Performance?

 

Submitted by Amy Sercel MS RD CD

Edited by Marcia Bristow MS RDN CSSD CD

Carbohydrates are the preferred source of energy for your brain and muscles.  When you eat carbohydrates in fruits, vegetables, grains, beans, dairy products, or sweets, they are converted into glucose and either used to provide immediate fuel for your muscles and brain, or stored as glycogen to be used for fuel later.  Conventional recommendations suggest that everyone get 45-65% of their calories from carbohydrates to ensure there is enough fuel to support daily activities and exercise.  For the average person who needs 2000 calories per day, this might mean eating around 250 grams of carbohydrates; for an athlete with much higher calorie needs than the average person, this could mean eating closer to 400 grams of carbohydrates per day or more.  The ketogenic diet, however, has people questioning whether carbohydrates are really the ideal fuel for athletes.

On the ketogenic diet, people get 75-80% of their calories from fat and 12-20% of their calories from protein, and eat less than 20 grams of carbohydrates per day.  It was originally designed as a therapeutic diet prescribed to children with epilepsy.  When your brain doesn’t have glucose to use for energy, your body converts fat into compounds called ketone bodies, which the brain can use for fuel.  People have begun following the ketogenic diet with the idea that it will force the body to burn fat for energy instead of carbohydrates.  Since the body stores more fat than glycogen, this would allow the athlete to perform for longer without needing to eat more carbohydrates before running out of fuel.¹ 

There are very few scientific studies looking at the impact of the ketogenic diet on athletic performance.  From these studies, it appears that people following the ketogenic diet will experience adaptations that allow them to burn about twice as much fat during exercise than those following a typical high-carbohydrate diet.^1–3 It’s not clear whether this actually results in any performance benefit.  Additionally, some studies contain design flaws that prevent readers from drawing any firm conclusions.

For example, one study placed 20 male endurance athletes into either a high-carbohydrate diet (HCD) group or a low-carbohydrate ketogenic diet (LCKD) group based on their typical dietary intake.  The researchers found that people in the LCKD group burned more fat during exercise, increased their peak power during a sprint, and lost significantly more weight than those in the HCD group.  When the data is looked at more closely, though, it becomes apparent that the participants in the LCKD group started out with a significantly higher body fat mass than those in the HCD group. At the same time, the men in the HCD group were only provided with general guidelines about following a high-carbohydrate diet, but the LCKD group received sample meal plans and shopping lists to help them follow the ketogenic diet.³ Having more information about the diet they needed to follow and starting with a higher body fat mass makes it more likely that the men lost weight simply as a result of following a more regimented diet, and makes it impossible to claim that any improvements in physical performance are due to diet alone.

Another commonly-cited study looked at endurance runners and triathletes who consumed a ketogenic diet for almost two years and found that they burned almost twice as much fat during activity than athletes eating a typical diet.  The study didn’t measure the impact of the ketogenic diet on the athletes’ physical performance.² There is a risk of research bias in this study, however, because it was funded by Quest Nutrition and the Atkins Foundation.  Quest Nutrition makes low-carbohydrate sports nutrition products, and the Atkins Foundation is run by Dr. Robert Atkins, the same individual who created the low-carbohydrate Atkins diet.

One study does examine the impact of the ketogenic diet on both fat burning and exercise performance.  Like the others, the researchers found that subjects following a low-carbohydrate diet did burn more fat during exercise.  However, the participants on the ketogenic diet needed to take in more oxygen while they exercised because the body uses more oxygen to turn stored fat into energy than it does to turn glycogen into energy.  As a result, the athletes’ overall physical performance was worsened by the ketogenic diet.¹

Taken together, these studies show the need for more, well-designed research on the impact of the ketogenic diet on athletic performance in addition to its influence on the body’s ability to burn fat.  Until that research is available, it is best to continue following the evidence-based recommendation to use carbohydrates to fuel your workouts.  Fuel up on whole grains, low-fat dairy, and fruit before a workout, bring snacks to keep you energized during exercise, and make sure to eat plenty of carbohydrates and protein to help recover from your activity.

References:

1.         Burke LM, Ross ML, Garvican-Lewis LA, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol. 2017;595(9):2785-2807. doi:10.1113/JP273230.

2.         Volek JS, Freidenreich DJ, Saenz C, et al. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism. 2016;65(3):100-110. doi:10.1016/j.metabol.2015.10.028.

3.         McSwiney FT, Wardrop B, Hyde PN, Lafountain RA, Volek JS, Doyle L. Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes. Metabolism. doi:10.1016/j.metabol.2017.10.010.

Simplifying Dinner, One Meal Kit at a Time

Meal Kit Service	Unique Features	Weekly Cost for 3 Recipes Serving 2 People	Meal Plans/ Dietary Preferences	Select Your Own Meals?	Additional Features
Hello Fresh	RD-approved recipes	$59.94	Classic Plan Veggie Plan Family Plan	Only with Classic Plan	Wine club – 6 bottles of wine per month for $89 Manage subscription on an app
Blue Apron	Sustainability-focused	$59.94	Two-Person Plan Three-Person Plan	Yes	Wine club – 6 small bottles of wine per month for $65.99 Purchase kitchen equipment with recipes Manage subscription on an app
Green Chef	90-95% certified organic Offset 100% of carbon emissions	$80.94	Omnivore Carnivore Vegetarian Vegan Gluten-Free Paleo Keto	No, but can adjust dietary preferences to change weekly meals	Website includes informational articles, such as kitchen safety and safe food handling tips
Sun Basket	70% certified organic	$74.93	Chef’s Choice Lean & Clean Paleo Vegetarian Gluten-Free	Yes	Website includes blog with informational nutrition articles
Plated	Antibiotic-free pork and poultry Hormone-free beef Organic whenever possible	$71.70	Two, Three, or Four servings per night	Yes	Add dessert to your weekly meals for an additional charge Manage subscription on an app
Home Chef	Cook up to 6 meals per week Sources ingredients from three family-owned companies	$59.70	Cook between two and six meals per week for two, four, or six people	Yes, from 11 options	Add a fruit basket, smoothie, or “premium meal” for an additional charge
Purple Carrot	Plant-based meals	$72.00	Three meals per week for 1-2 people Two meals per week for 3-4 people High-Performance Meals	No	High-Performance Meals created with Tom Brady and designed to be higher in protein and lower in carbohydrates

 

Submitted by Amy Sercel MS RD CD

Edited by Marcia Bristow MS RDN CSSD CD

For many people with busy schedules, meal kits provide an easy answer to the question, “What’s for dinner tonight?”  When you subscribe to a meal kit, all the ingredients you need to make several recipes are delivered right do your doorstep, pre-portioned in the amounts you will need to make each recipe.  Meal kits have become popular recently, and there are many different services available. 

Each meal kit service ships you an insulated box every week containing all you’ll need to prepare your recipes.  When you select your recipes you’ll have the opportunity to see the nutrition facts information for each.  The recipes’ calorie contents range from 500-800 calories in each meal kit service.  For the most part you can recycle all of the packaging, bring the insulation to an industrial composting facility, and save any ice packs they provide to re-use later on.  The services all assume you have some basic ingredients on hand, like salt, oil, and butter, so these will not be included in your box.  If you’re thinking of trying a meal kit, read on to learn the differences between each service and find out which one would be right for you and your family.

Hello Fresh¹ - $8.74-9.99 per serving, includes shipping

Hello Fresh appears to be the only meal kit service with recipes that have been approved by a Registered Dietitian.  There are three plans you can choose from, depending on your dietary preferences and the number of Hello Fresh meals you’d like to make each week:

• The Classic Plan includes meals with meat, shellfish, and produce.  This plan provides three or four recipes per week that serve two or four people.  This is the only plan that allows you to choose the recipes you will make.
• The Veggie Plan includes vegetarian meals that contain plant-based protein and whole grains.  This plan provides three recipes per week that serve two or four people. 
• The Family Plan is designed to provide quick and easy-to-prepare meals that a variety of audiences will enjoy.  The plan includes two or three recipes per week that serve four people. 

Some recipes include Pesto Panko Chicken with Green Salad, Honey-Glazed Pork Tenderloin with Sweet Potatoes and Green Beans, and Spiced Dijon Salmon with Apple Arugula Salad and Couscous.  Hello Fresh has an app you can use to view the recipes you’ll get for the next week (and choose them if you have the Classic Plan), decide when you want your box to be delivered, and manage your account.  They also offer a wine club in which you can receive 6 bottles of wine per month for an additional $89.  These wines are designed to pair with the recipes provided.

Blue Apron² - $8.99-9.99 per serving, includes shipping

Blue Apron was the first meal kit service offered, and as a result their website seems to be the most comprehensive.  Sustainability is an integral part of their message.  Blue Apron claims to promote sustainability by using grass-fed and pasture-raised beef, seafood recommended by Food and Water Watch, livestock raised without antibiotics or hormones, and food produced without genetic modification.³ Like Hello Fresh, Blue Apron also offers several different plans:

• The Two-Person plan provides either two or three recipes per week that serve two people.  Exclusively vegetarian recipes are only offered through this plan.
• The Family Plan provides two, three, or four recipes per week that all serve four people.

Once you select and purchase a plan, you will be able to tailor your dietary preferences and choose the recipes you would like to receive.  Some of Blue Apron’s recipes include Sweet & Spicy Beef with Wonton Noodles, Basil Pesto Spaghettini, and Roasted Chicken with Goat Cheese Mashed Potatoes and Sautéed Carrots. 

Blue Apron also has an app where you can find recipes and view how-to videos if you need help with any cooking techniques.  Additionally, for $65.99 per month you can sign up to receive six bottles of wine.  These bottles are 2/3 the size of a typical bottle of wine and are designed to be shared by two people.

Green Chef⁴ - $10.49-14.99 per serving, shipping not included

Green Chef was rated the best meal kit service by USA Today because the recipes were the most flavorful, convenient, and fun to make.⁵ 90-95% of Green Chef’s ingredients are certified organic and the service claims to offset 100% of their carbon emissions through sustainable practices.  Green Chef also offers a wide range of menu options in either a two-person or family plan, both of which have the same per-serving cost.  The two-person plan provides three recipes that serve two people, and the family plan provides two recipes that serve four.  Only the Omnivore and Carnivore menus are available on the Family Plan. 

• Omnivore includes meat, seafood, and vegetarian meals.  You can choose not to receive meals that contain beef, poultry, lamb, shellfish, fish, or game if they do not fit into your preferred meal pattern.
• Carnivore provides meat or seafood in each meal.
• Vegetarian provides meat-free meals that still include dairy and eggs. 
• Vegan includes only plant-based protein.
• Gluten-Free provides two meat or seafood and one vegetarian dinner per week, all of which contain no gluten.
• Paleo does not include processed foods, grains, legumes, or dairy, and instead is high in meat and vegetables.
• Keto offers low-carbohydrate meals that don’t contain dairy or grains.

Once you select a plan and set your dietary preferences, Green Chef will automatically select two or three recipes that you will receive.  This is different from Hello Fresh or Blue Apron, which allow you to select your recipes from a list every week.  You can change the recipes you are scheduled to receive by changing your dietary preferences; for example, if you do not like the beef recipe one week, you can modify your dietary preferences to exclude beef for that week.  Some of Green Chef’s recipes include Tamarind Glazed Tempeh, Moroccan Chicken Tangine, or Spanish Egg’n’Hash.  Their recipes provide a variety of different vegetables and grains.

Sun Basket⁶ - $9.99-11.49 per serving, shipping not included

Sun Basket states that 70% of their ingredients are certified organic and hope that all ingredients will be organic by the beginning of 2018.  They claim that all of their meat and poultry is antibiotic-free, their lamb, chicken, and poultry are pasture-raised, their dairy products and eggs are organic, and their seafood is certified for sustainability by the Marine Stewardship Council.  You can choose between the Classic Plan that provides three recipes per week that serve two or four people or the Family Plan that provides two, three, or four recipes per week that serve four people.  Within these, you can also choose one of several meal plans:

• Chef’s Choice provides a variety of meat, seafood, and vegetarian dishes.
• Paleo includes recipes that do not contain grains, soy, corn, dairy, and gluten.
• Lean & Clean limits meals to 550 calories per serving and does not include gluten, dairy, or added sugar.  This meal plan is not available on the Family Plan.
• Gluten Free includes meat, produce, and gluten-free grains.
• Vegetarian includes produce and plant-based protein.

Like Hello Fresh and Blue Apron, you can choose your recipes for the week from a larger list after you select your meal plan.  Some of Sun Basket’s recipes include Steak Salad with Romanesco Vinaigrette, Burmese Salmon Salad with Lemongrass and Apple, and Chorizo and Tomatillo Chili with Coconut and Lime.  Each recipe should take less than thirty minutes to prepare.  

Plated⁷ – $9.95-11.95 per serving, shipping not included

Plated allows you to choose from 17 recipes each week, offering a little more flexibility even though they do not provide meal plans for specific diets.  Their pork and poultry are raised without antibiotics, beef is raised without hormones, seafood is sustainably caught, produce is seasonal, and ingredients are organic whenever possible.  Plated allows you to choose two or four recipes per week and gives you the option for two, three, or four servings per recipe.

Once you sign up for a plan you will be able to select the recipes you’d like to make.  You can also add or subtract recipes each week.  Some of their recipes include Sticky Sesame Cauliflower with Vegetable Fried Rice, Spaghetti and Chicken Meatballs with Creamy Cherry Tomato Sauce, and Crispy Flounder with Miso Ratatouille.  Plated also offers telephone support, so you can give them a call if you get stuck while preparing any of their meals.  You can also add dessert for an additional charge.

Home Chef⁸ - $9.95 per serving, shipping included when spending over $45

Home Chef allows you to choose between 11 recipes per week.  When you select your meal plan you will be able to choose ingredients you want more often (such as vegetables), and any ingredients you’d like to avoid (such as meat, dairy, and mushrooms).  Home Chef will automatically choose three recipes for you based on your preferences.  If you are vegetarian or have other dietary restrictions, your options will be more limited because there may be only two or three recipes that meet your dietary need available that week. 

Although this service doesn’t offer specific meal plans to choose from, it does allow you to purchase more meals per week than any other meal kit service.  With Home Chef, you can order between two and six meals each week that serve two, four, or six people; most of the other meal kit services provide a maximum of three or four meals per week.

Some of the recipes include Sun-Dried Tomato Pesto Spaghetti with Tomato Bruschetta, Sirloin Steak alla Modena with Potatoes and Broccoli, and Cod Amandine with Wild Rice Pilaf.  Home Chef’s recipes may not contain as many vegetables and whole grains as the recipes of other meal kit services, which may be important to consider if you are thinking of purchasing six meals per week.

Purple Carrot⁹ - $10-13 per serving, includes shipping

Purple Carrot provides 100% plant-based recipes, making this a good option for vegetarians or vegans.  One of this company’s objectives is to introduce people to a wider variety of plant foods, and their website cites many health benefits of choosing a plant-based diet.  Other reviewers appreciated the fact that the recipes provided a lot of leftovers and said the meals provided delicious flavors and textures.⁵ Purple Carrot offers three possible meal plans:

• Three meals per week for 1-2 people
• Two meals per week for 3-4 people
• Three “high performance” meals per week for 1-2 people.  These meals contain more protein and are all gluten-free and are created in collaboration with Tom Brady based on the diet he follows to enhance his performance.

Once you sign up for a plan, you will not have the option to select the recipes you receive.  Some of Purple Carrot’s recipes include Ginger Tofu with Broccolini and Carrot Dressing, Thai Coconut Rice Bowl with Roasted Carrots and Cilantro-Mint Chutney (from the Performance Meals), and Mediterranean Eggplant with Chermoula and Apricot Couscous.  The nutrition information for each recipe is available online.

The Bottom Line

Meal kits can be a great time saver by reducing the amount of time you’ll need planning meals, buying ingredients in the grocery store, and actually cooking.  They might also reduce food waste since you are given the exact amount of each ingredient you need.  This would be especially helpful if you’re an adventurous eater who likes to try new foods but doesn’t know what to do with the “extra” you have left over after preparing a recipe.  You can also look at the nutrition facts for each recipe before you finalize your menu for the week, so you’ll be able to choose the meals that best meet your needs.

You may be more interested in one meal kit service or another depending on your food values, dietary preferences, and degree of control you want to have over your menu selections.  Each service offers around $30 off for your first week and you have the option to suspend or cancel your membership at any time without any additional cost.  If you’re having trouble deciding which service fits best with your food preferences, consider trying a few of them before you make the final decision.  No matter what, you’ll be introduced to new foods and have fun in the kitchen!

References:

1.         Our Weekly Meal Plans | Fresh Food Delivery | HelloFresh. https://www.hellofresh.com/food-boxes/. Accessed September 18, 2017.

2.         Blue Apron: Fresh Ingredients, Original Recipes, Delivered to You. https://www.blueapron.com/. Accessed September 14, 2017.

3.         Blue Apron: Fresh Ingredients, Original Recipes, Delivered to You. https://www.blueapron.com/pages/vision. Accessed September 18, 2017.

4.         Green Chef: Organic. Delicious. Delivery. https://greenchef.com/home. Accessed September 14, 2017.

5.         Leonhardt M. This Is the Best Meal-Kit Service on the Market Right Now. Money. http://time.com/money/4856342/best-meal-kits-value/. Accessed September 18, 2017.

6.         Sun Basket | Healthy, Organic and sustainable Meal Kit Delivery. https://try.sunbasket.com/?offer=A-LQSEM35&SCID=GCPC&utm_source=Adwords&utm_medium=LQSEM&utm_campaign=NB:General:EC:S:G&utm_term=MID&test=&sl=&utm_audience=Classic_CC&utm_adset=Text&akd=213199086882+kwd-12836190414+c. Accessed September 14, 2017.

7.         Plated | Cook more. Live better. Plated. https://www.plated.com/?utm_medium=search&utm_source=google_brand&utm_campaign=PR_Newengen_Brand_Plated_Meal_Delivery_v2+l_DE1+a16b&utm_term=plated%20meal%20kit&utm_content={AdGroup}&cvosrc=ppc.google.plated%20meal%20kit&cvo_creative=218843050933&cvo_pid={AdGroup}&cvo_campaign=PR_Newengen_Brand_Plated_Meal_Delivery_v2+l_DE1+a16b&cvo_crid=218843050933&matchtype=e. Accessed September 18, 2017.

8.         Home Chef Meal Delivery Service, Fresh Ingredients to Cook at Home. Home Chef. https://www.homechef.com/sign-up/welcome. Accessed September 18, 2017.

9.         Purple Carrot | How it Works. https://www.purplecarrot.com/how-it-works. Accessed October 3, 2017.

The Great Debate: Carbs vs. Fat

 

Submitted by Amy Sercel MS RD CD

Edited by Marcia Bristow MS RDN CSSD CD

A few weeks ago, the media yet again caught onto a new nutrition study.  You might have heard about it in an article titled something like “Large diet study suggests it’s carbs, not fats, that are bad for your health,”¹ “New study favors fats over carbs,”² or even, “Large-scale dietary study: fats good, carbs bad.”³ Many of these articles dramatically over-simplify the original research.

The study analyzed the diets of 135,335 people living in 18 different countries, then followed these people for an average of 7 years to track their health outcomes.  After seven years, the researchers compared participants’ original dietary patterns to their risks of dying from any cause, developing cardiovascular disease, and dying from cardiovascular disease during the time of the study. 

Researchers found that the risk of dying from any cause increased as people ate more carbohydrates.  Specifically, when carbohydrates made up about 77% of a person’s total calorie intake, they were 12-22% more likely to die during the study than when carbohydrates made up about 46% of total calorie intake.⁴ Right now, it’s recommended that 45-65% of your calories come from carbohydrates

On the other hand, people who consumed an average of 35% of their calories from fat had a 5-10% lower risk of death, heart disease, stroke, or heart attack than people who only consumed about 10% of their calories from fat.  Furthermore, people with higher intakes of saturated fat were not any more likely to develop heart disease, have a heart attack, or die from a heart attack.⁴ The highest intake of saturated fat was around 12% of total calories.  The current recommendations suggest that 20-35% of calories come from all types of fat, and no more than 10% of calories come saturated fat.

It’s interesting to compare the original research to the articles published in the media.  These articles seem to promote the idea that all carbohydrates are “bad.”  This may lead you to believe you should stop eating carbohydrates altogether and eat more of all types of fat.  In reality, the original research article does not recommend doing so.  The researchers did not find any health benefit when carbohydrate intake was less than 50% of calories.⁴

Furthermore, carbohydrates come from a wide variety of foods.  While it’s true that foods like candy, soda, and refined flour are all sources of carbohydrates, you also get carbohydrates from fruits, vegetables, dairy products, beans, nuts, and whole grains.  These foods provide important vitamins and minerals, as well as fiber and antioxidants that have been shown to protect against certain diseases.

There are several limitations to this study that make it difficult to draw conclusions that apply to the average person’s diet.  Most significantly, the researchers did not differentiate between the sources of participants’ carbohydrates, and the authors admit that the countries with the highest carbohydrate intakes tend to eat large quantities of white rice and white bread.⁴ It’s already known that eating a diet high in refined carbohydrates and sugar elevates your blood sugar and may lead to insulin resistance, which in turn can cause your liver to secrete more triglycerides into your blood because your cells aren’t getting the energy they need from carbohydrates.  As a result, you may be more likely to develop cardiovascular disease if your sugar intake is high.⁵

At the same time, peoples’ needs for carbohydrates, protein, and fat vary significantly based on their lifestyle and activity levels.  For example, endurance athletes may need up to 70% of their calories to come from carbohydrates to make sure that their muscles have enough fuel to keep them going during an athletic event.  This is important for athletes, but would not necessarily be healthy for someone who is less active.  More follow-up studies are needed to confirm this study’s findings before any of the current nutritional recommendations can be modified.   

Rather than changing your diet based on one research study, meet with a Registered Dietitian who can provide you with individualized, evidence-based recommendations based on your unique lifestyle and needs.  Reduce your intake of refined carbohydrates like white flour and foods high in sugar, and make an effort to choose whole grains, fruits, vegetables, beans, lean protein, and unsaturated fats whenever possible.  These general recommendations have stood the test of time and are not going to change based on one research study.

References:

1.         Large diet study suggests it’s carbs, not fats, that are bad for your health - CBS News. https://www.cbsnews.com/news/large-study-suggests-carbs-not-fats-bad-for-you/. Accessed September 12, 2017.

2.         Bakalar N. New Study Favors Fat Over Carbs. The New York Times. https://www.nytimes.com/2017/09/08/well/new-study-favors-fat-over-carbs.html. Published September 8, 2017. Accessed September 12, 2017.

3.         Large-Scale Dietary Study: Fats Good, Carbs Bad - Slashdot. https://science.slashdot.org/story/17/08/30/0444248/large-scale-dietary-study-fats-good-carbs-bad. Accessed September 12, 2017.

4.         Dehghan M, Mente A, Zhang X, et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. The Lancet. August 2017. doi:10.1016/S0140-6736(17)32252-3.

5.         Insulin Resistance and Lipid Disorders. Medscape. http://www.medscape.com/viewarticle/584885. Accessed September 12, 2017.