Ketogenic Diets: Fat-Filled Lies Won’t Make You Slim (or a Better Athlete)

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How do you turn your body into a fat burning machine, run faster than Usain Bolt, recover from exercise immediately and wake up each day bursting with energy? According to some people, the ketogenic diet is your answer (learn the basics of this diet here). This high-fat, moderate protein diet that is practically void of carbohydrates forces your body to use fat for energy. LeBron James supposedly tried it and offensive lineman decided to give it a shot after an ex-NFL center and O-line coach LeCharles Bentley recommended it. However, the offensive lineman and LeBron weren’t actually following a ketogenic diet. Though these athletes didn’t really know what they were following (no worries LeCharles, I’m sure your nutrition advice is on par with me coaching the O-line), people who actually follow it swear by it. Could this be an unconventional path to weight loss and better health? Unfortunately, the ketogenic diet craze has been fattened with misinformation.

Here is what I am covering in this post:

  • Eat Fat, Lose Fat? Does the ketogenic diet make you lose weight?
  • How does this diet impact muscle?
  • The ketogenic diet and athletic performance.
  • The issue with ketogenic research studies.

I am not covering “training low” or low carbohydrate  / non-ketogenic diets in this article.

Eat Fat, Lose Fat?

During the first several days on a ketogenic diet your weight will take a nosedive. Carbohydrate is stored in the form of glycogen in liver and muscle. Each gram of carbohydrate is stored with 3 – 4 grams of water. Decrease your carbohydrate intake, use glycogen and you’ll lose water weight very quickly. Weight loss, even if from water, can motivate people driven by the number on the scale. Given that adherence is the number one predictor of weight loss when on a diet, we can’t discount psychological effect of the number on the scale going down.

What happens if you stay on the diet? A group of NIH researchers admitted seventeen overweight or obese men to a metabolic ward and placed them on a high carbohydrate baseline diet for four weeks followed by four weeks on an isocaloric ketogenic diet (this diet contained the same amount of calories as the high carbohydrate baseline diet). The men lost weight and body fat on both diets. The ketogenic diet did not lead to greater fat loss as compared to the high carbohydrate diet and in fact body fat loss slowed during the ketogenic diet and subjects lost muscle (1). Time to chuck the “carbohydrates make you fat” books in the recycling bin.

What about other studies showing ketogenic diets help athletes lose body fat and maintain performance? These studies were not actually using a ketogenic diet protocol but instead were high fat, high protein, low carbohydrate diets. Also, none of the studies measured if the study subjects were actually in nutritional ketosis (2, 3, 4).  See the section on The Issue with Ketogenic Research Studies for more information on this topic.

Ketogenic diet and weight

Regardless of the studies indicating the ketogenic diet will not lead to greater weight loss as compared to a diet composed of the same amount of calories, some may lose weight because they will end up cutting down on their favorite foods. Fewer food choices often means fewer calories consumed.

Muscle Up with the Ketogenic Diet?

The ketogenic diet isn’t high enough in protein for maximal muscle gains. Using the lower end of fat intake on a classic ketogenic diet (80% of calories), one could consume 15% of calories from protein (112 grams) on a 3,000-calorie diet. Protein requirements are at least 1.2 – 1.8 grams of protein per kilogram bodyweight (or 0.55 – 0.82 grams per lb. bodyweight) per day if training and eating a diet with enough calories to maintain weight. Protein needs go up if you are cutting calories to spare the breakdown of muscle tissue when dieting. On this diet, 112 grams of protein equals just under 1.3 grams of protein per kg bodyweight for a 200 lb. person and even less for anyone who weighs more.

In addition to inadequate protein intake, “the ketogenic diet reduces many of the signaling molecules involved in muscle hypertrophy (growth),” states Dr. Antonio Paoli, M.D., B.Sc., Associate Professor and Vice Dean of the School of Human Movement Sciences, University of Padova. Without getting too technical, even with sufficient calorie intake, the ketogenic diet suppresses the IGF-1 / AKT / mTOR pathway (5). Using ketones for energy slows muscle breakdown. However it doesn’t stop this process (5).

The Ketogenic Diet and Athletic Performance

Once fully adapted to a ketogenic diet, athletes can supposedly rely on a seemingly endless supply of body fat for energy. No need for carbohydrate gels, beans, gummies and sports drinks every 15-30 minutes during long runs, rides or triathlons to sustain energy levels. Fewer calories consumed may make it easier for some people to stay within their total daily calorie needs (though if you are training that much staying within your calorie requirements shouldn’t be difficult).

Trading carbs for fat seems like a huge benefit for athletes, particularly endurance athletes who train and compete for several hours at a time (6). In addition to utilizing body fat, fat actually produces more energy (ATP) (5). However, fat is a slow source of fuel (see graphic below), the human body cannot access it quickly enough to sustain high-intensity exercise and therefore, this diet is really only (potentially) applicable to ultra-runners and triathletes competing at a relatively moderate to slow pace.

In a ketogenic diet study examining athletic endurance, researchers had subjects cycle at a snails pace (equivalent to a heart rate of about 120 beats per minute for anyone 20-30 years old or 115 for a 40 year old) until they became exhausted before and after 4-weeks on a ketogenic diet. There were no differences in the amount of time they were able to cycle before getting tired prior to or after the four-week ketogenic diet (7). In studies examining high fat diets (not ketogenic and ketones weren’t measured) and endurance performance, study subjects relied on more fat as opposed to carbohydrate during low intensity exercise, yet there was no clear performance advantage on the higher fat diet (8). A recently published study examined 20 elite ultra-marathoners and Ironman distance triathletes. Some were habitually consuming a traditional high carbohydrate diet while the other group was following a ketogenic diet (slightly adjusted macronutrient ratios yet they were in ketosis as measured by blood ketone levels). As expected, those following a higher fat diet used a greater percentage of fat for energy while the higher carbohydrate diet group used more carbohydrate for energy during a 180 minute submaximal running test (I’d call that leisure running intensity). There was no difference in calories burned over the course of the run. Both groups had the same level of perceived exertion and there was no test to determine performance differences between groups (9).

If there’s no performance benefit and we know carbohydrates work, why follow this diet? If your primary goal is weight loss, it doesn’t matter if you use more fat than carbohydrate while exercising (SN: can we please stop talking about the fat burning zone) as long as you’re burning more total calories over the course of the day. Plus, in the interest of (if you are not an ultra endurance athlete) jack up the intensity and burn as many calories in a short period of time as possible. Unfortunately, a ketogenic diet won’t help you do that – when relying on fat for fuel, the intensity of your exercise will drop – the body simply can’t access fat (a slow source of energy) quickly enough to sustain high-intensity exercise. Instead, carbohydrates are necessary for high intensity activity.
ketogenic diet and sports

The Issue with Ketogenic Research Studies

Here’s the issue with many ketogenic research studies and media reports based on them: in most cases, the study subjects were not actually following a ketogenic diet – they were following a higher fat, high-protein low carbohydrate diet (10, 11, 12). Each person’s carbohydrate and protein limits needed to stay in ketosis vary and therefore, measuring ketones through blood or urine is the only definitive way to determine if you are in ketosis. Complicating matters more, low carbohydrate diets (including ketogenic diets) lead to a substantial drop in carbohydrate content, and associated water stored with it, in muscle. This change overestimates the drop in lean body mass as measured by DEXA.

ketogenic and low carbohydrate diets

There are no modifications, higher protein intakes or “on again, off again” (where you go on it one day and off it the next) to this diet. You must be in a state of nutritional ketosis or you will need to decrease carbohydrate and protein intake even further to get into nutritional ketosis and rely on ketones for energy.

Is There Any Benefit?

Ketogenic diets help decrease incidence and severity of seizures in epileptic patients (this is what the diet is intended for). Also, ketogenic diets may be beneficial when implemented soon after a traumatic brain injury (including concussion) (13). In addition, scientists are examining if this diet is beneficial for diseases that affect the brain such as Alzheimer’s.

If you want to lose weight, the ketogenic diet is not superior to a reduced calorie diet. Also, unless you are an ultra endurance athlete who just loves dietary fat, hates eating at social occasions and can put up with the potential side effects from this diet it isn’t for you.
Now where is the O-line? I’ve got some coaching to do…

References

1 Hall KD, Chen KY, Guo J, Lam YY, Leibel RL, Mayer LE, Reitman ML, Rosenbaum M, Smith SR, Walsh BT, Ravussin E. Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Am J Clin Nutr. 2016 Jul 6. [Epub ahead of print]

2 Zajac A, Poprzecki S, Maszczyk A, Czuba M, Michalczyk M, Zydek G. The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists. Nutrients 2014;6(7):2493-508.

3 Rhyu HS, Cho SY. The effect of weight loss by ketogenic diet on the body composition, performance-related physical fitness factors and cytokines of Taekwondo athletes. J Exerc Rehabil 2014;10(5):326-31.

4 Paoli A, Grimaldi K, D’Agostino D et al. Ketogenic diet does not affect strength performance in elite artistic gymnasts. JISSN 2012;9:34.

5 Paoli A, Bianco A, Grimaldi KA. The ketogenic diet and sport: a possible marriage? Ex Sports Sci Reviews 2015.

6 Volek J, Noakes T, Phinney SD. Rethinking fat as a fuel for endurance exercise. Eur J Sport Sci 2014;2:1-8.

7 Phinney SD, Bistrian BR, Evans WJ, Gervino E, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism 1983;32(8):769-76.

8 Burke LM, Kiens B. “Fat adaptation” for athletic performance: the nail in the coffin? J Appl Physiol 2006;100(1):7-8.

9 Volek J, Freidenreich DJ, Saenz C, Kunces LJ, Creighton BC, Bartley JM, Davitt pm, Munoz CX, Anderson JM, Maresh CM, Lee EC, Schuenke MD, Aerni G, Kraemer WJ, Phinney SD. Metabolic characteristics of keto-adapted ultra-endurance runners. Metab Clin Exp 2016;65(3):100-110.

10 Tinsley GM, Willoughby DS. Fat-Free mass changes during ketogenic diets and the potential role of resistance training. Int J Sport Nutr Exerc Metab. 2015 Aug 12. [Epub ahead of print]2 Rouillier MA, Riel D, Brazeau AS, St. Pierre DH, Karelis AD. Effect of an Acute High Carbohydrate Diet on Body Composition Using DXA in Young Men. Ann Nutr Metab 2015;66:233-236

11  Paoli A. The ketogenic diet and sport: a possible marriage? Ex Sci Sports Sciences Rev 2015;43(3):153-62.

12  Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am Society Clin Nutr 2008;87(1):44-55.

13 Nutrition and Traumatic Brain Injury: Improving Acute and Subacute Health Outcomes in Military Personnel (2011). The National Academies Press, Institute of Medicine. Washington DC. 2011 http://www.nap.edu/read/13121/chapter/15

 

Are Low Carbohydrate Diets Best for Weight Loss?

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If you haven’t been bombarded with advertising for low carbohydrate foods, diets, plans and crazed anti-carbohydrate friends and coworkers in the past few years, you must be living on a remote island somewhere (taking any visitors?). The anti-carbohydrate, pro-fat crowd (including keto, Paleo, and Whole 30 – aka Paleo reinvented) devotees might be onto something. But that “something” isn’t a miraculous cure for obesity. Should you trade your low fat, higher carbohydrate diet for full fat foods and “bread” made from cauliflower and mozzarella cheese? It’s time to look past the media headlines to the latest research on low fat vs. low carbohydrate diets.

In this article I’ll cover:

  • the latest research on lower carbohydrate diets;
  • what this research means for you; and
  • a sidenote on the insulin hypothesis.

Should you switch to low carbohydrate vs. high carbohydrate foods?

The Latest Research on Low Carbohydrate Diets

In an attempt to determine which diet is best for weight loss, one of the latest studies collected and analyzed studies on low fat and low carbohydrate diets. A systematic review and meta-analysis, which combines the results of several studies, compared intervention studies > 1 year in length where participants were placed on low fat diets, low carbohydrate diets, other high fat dietary interventions or they continued eating whatever they wanted (their typical diet). Low fat diets ranged from  < 10% of calories from fat to < 30% of calories from fat. The diet interventions used ranged from providing instructions at the start of the study and expecting participants to follow the diet plan to regular counseling sessions with dietitians, food diaries and cooking lessons to actual feeding studies where participants were given most of their overall food intake (with the last approach the most well-controlled). Some studies coached participants to cut calories while others, including those put on low-carbohydrate Atkins-style diets, were told to eat until they were full without worrying about calories.

They analyzed results from 13 trials that examined weight maintenance as well as studies that didn’t include weight loss as a primary goal. In these studies low-fat and high-fat diets lead to a similar amount of weight loss. Low-fat diets were superior only when compared to the subjects’ normal diet – in other words actually going on a diet led to greater weight loss than not dieting (no surprise there). The tiebreaker came from an analysis of 35 weight loss trials, 29 of which were conducted using adults who were overweight, obese, or had type II diabetes. Overall, there was no difference between low-fat and high-fat diet interventions. Low-fat diets led to greater weight loss compared to groups who didn’t diet. However, higher fat diets were the clear winner (according to the headlines), leading to significantly greater weight loss after a year than low fat diets. Before tossing out your steel cut oatmeal, whole-grain bread and fresh Summer fruit, let’s take a closer look at this data. It was pulled from a comparison between low-fat diets and high-fat diets that varied by more than 5% of calories. So did low carbohydrate, higher fat diets really win or was it because subjects cut calories? Is it easier to cut calories on low carbohydrate, high fat diets? Participants on low carbohydrate diets lost about 2.2 pounds more weight after one year versus those on a low-fat diet. A 2.2-pound difference in weight loss after one year on a diet isn’t very impressive, especially considering many of the subjects were overweight or obese to begin with.

The End of Higher Carbohydrate, Low-Fat Diets?

Based on these results the authors suggest low-fat diets shouldn’t be the go-to recommendation for weight loss. However, the results of this study are mainly applicable to overweight, obese and type II diabetics – the primary populations examined in these studies. We can’t take the authors conclusion that low carbohydrate, higher fat diets are better if you are looking to lose a few pounds for a beach ready body. What works for an obese adult or type II diabetic will not necessarily work for an active adult who wants to get a 6-pack. Secondly, previous research shows low carbohydrate diets tend to produce greater weight loss, initially, than low fat diets (some of this is water weight since carbohydrates store 3-4 times their weight in water in the form of glycogen in muscles and the liver and your glycogen stores will start dropping when you drastically lower your carbohydrate intake) yet after a year, weight loss is equivalent between both diets. Other research shows weight loss over the first six months on a diet is the main predictor of both weight loss success and sticking to a diet over the long-term. Greater weight loss initially = better adherence = better success over time.

Long-term Success

What’s more disappointing than the paltry 2.2-pound difference between the low-fat and high-fat diets after one year is the total average weight loss in the studies designed for weight loss – a mere 8.25 lbs. after 1 year. Instead of declaring low carbohydrate, higher fat diets a clear winner over low fat, higher carbohydrate diets (especially considering the 2.2 pound difference), we should be asking why it’s tough to stay on a diet, any diet? Why aren’t study participants losing more weight? I don’t have the answer to these questions and leading weight loss researchers don’t seem to have a complete picture right now either.

If you want to lose weight, choose a lower calorie diet primarily based on high quality foods or create your own plan that fits into your lifestyle and is one you can stick with it. There are many diets that could, potentially, work for you. If you want to try a low carbohydrate diet for a while, by all means go for it (especially if you need to see that number on the scale move pretty quickly)! If cutting carbs sounds like being in detention, then skip that approach! I’m giving you permission to alter your plan as often as you need to based on changes in your lifestyle (some research papers actually suggest doing this and I am a huge fan of this approach), motivation, and results.

Conceptually, low carbohydrate diets are very easy. You don’t have to worry about portion sizes, log calories, count points or determine if you have to eat less at dinner to make up for a lunchtime splurge. Decision-making is boiled down to: it contains carbs and therefore off my diet or it is low in carbs and the carbs it does contain are high in fiber so I can eat it. Just don’t buy into the hype that low fat, higher carbohydrate diets are the only way to lose weight or that these diets are better, over the long term, than other dietary approaches that also cut calories.

References

Tobias DK, Chen M, Manson JE, Ludwig DS, Willett W, Hu FB. Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis. Lancet Epub before print. 29 October 2015.

Greenberg I, Stampfer MJ, Schwarzfuchs D, Shai I; DIRECT Group. Adherence and success in long-term weight loss diets: the dietary intervention randomized controlled trial (DIRECT). J Am Coll Nutr 2009;28(2):159-68.

Franz MJ, VanWormer JJ, Crain AL, Boucher JL, Histon T, Caplan W, Bowman JD, Pronk NP. Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up. J Am Diet Assoc 2007;107(10):1755-67.

Hall KD. Predicting metabolic adaptation, body weight change, and energy intake in humans. Am J Physiol Endocrinol Metab 2010;298(3):E449-66.

Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet 2011; 378(9793).

Rosqvist F, Iggman D, Kullberg J, Cedernaes J, Johansson HE, Larsson A, Johansson L6, Ahlström H, Arner P, Dahlman I, Risérus U. Overfeeding polyunsaturated and saturated fat causes distinct effects on liver and visceral fat accumulation in humans. Diabetes 2014;63(7):2356-68.