How to Systematically Test if Keto is Right for You

This is a sample chapter taken from the second edition of our Muscle and Strength Pyramid: Nutrition book. The book is now in its third edition, but the content is still relevant.

How to Tell if You Would Do Better With a Higher Fat-to-carbohydrate Ratio

Although it is not very typical among recreational and competitive bodybuilders and strength athletes to fall into this category, I think it is important to address how to tell if you are someone who would do better with a higher fat-to-carbohydrate ratio.

Now when I say “high fat”, I typically am referring to a fat percentage at or above 35% of total calories¹ as opposed to the aforementioned 15-30% recommendation (depending on whether you are dieting or gaining). In turn, keeping calories and protein the same, this higher fat intake leads to a generally lower carbohydrate diet compared to my earlier recommendations. And when I say “lower carbohydrate diet”, I’m referring to an intake that may approach as low as 0.5-1.5 g/lb (~1-3 g/kg) of bodyweight.

I am not necessarily referring to a ketogenic diet, which is extremely low in carbs, sometimes defined as 50g or lower². Ketogenic or ‘keto’ diets necessitate high fat intakes to maintain calorie balance, often at or above 60% of total calories. Keto diets have become quite trendy and popular as of late. Largely fueled by the idea that eating more dietary fat helps you to burn more fat as fuel, keeping you leaner along with the idea that you can only lose fat by keeping insulin low; however, these concepts aren’t quite accurate. Sure, you shift your body’s fuel usage more towards burning fat on a keto diet and insulin levels are lower, but since you are also consuming more fat, it doesn’t result in greater fat loss, and high insulin levels don’t predict body fat loss in a deficit³.

However, this isn’t to say keto diets are useless, but rather have pros and cons. In the literature relevant to sport, exercise, and body composition, they are a mixed bag of positive, negative, and neutral effects:

• There is an initial 1–4 week period of fatigue, irritability, and decreased performance when adopting a low-carb diet that subsides after adaptation

As you can see, in general, for healthy, athletic individuals performing resistance training, the potential pros are typically not worth the cons of adopting a low-carb diet. However, there may be a time and a place for a high-fat, low-carb diet, and most⁴⁵⁶⁷⁸ (but not all⁹) research indicates that when there is a time and place, the utility for low carb diets exist among people who are insulin resistant.

So, how do you know if you fall into this camp and could benefit from that type of diet?

Well first off, let me state that the vast majority of people reading this book don’t fit the bill. Insulin resistance is typically only common among sedentary individuals with obesity (and even then it’s not everyone) and it is often a temporary state, as insulin sensitivity improves with a healthier diet and exercise. With that said, there are some instances where exercising, non-obese individuals can be insulin resistant, which might indicate a higher-fat, lower-carb approach would be better.

Insulin resistance is typically increased with age¹⁰, a family history of diabetes¹¹¹², the presence of a condition in women called polycystic ovarian syndrome (PCOS)¹³, or oligomenorrhea¹⁴, which is represented by a menstrual cycle that occurs less frequently, specifically taking longer than 35 days to recur. While these first two factors can sometimes be affected by bodyweight and exercise, women with PCOS or oligomenorrhea typically have higher androgen levels (male sex hormones) than most women which predisposes them to be insulin resistant to some degree, regardless of activity or body-fat levels.

As you can see, in general, for healthy, athletic individuals performing resistance training, the potential pros are typically not worth the cons of adopting a low-carb diet.

Additionally, it is not at all uncommon for women with higher androgen counts to be disproportionately represented in athletic populations. This is even more so true in strength and power sports, which tend to have more women with higher androgen levels even compared to other sports¹⁵. But, don’t despair if you need to modify your diet due to potential insulin resistance if you are a woman with PCOS or oligomenorrhea. The upside is that you likely have a higher than normal androgen count, which may mean you potentially perform better on average than other athletes¹⁶. To further allay any fears, take heart that there is pretty convincing evidence that a higher-fat, higher-protein, lower-carbohydrate diet can be very effective for producing fat loss among those with insulin resistance¹⁷¹⁸¹⁹.

Now, what if you are a male who does not respond well to carbohydrates or a female who does not have a diagnosis of PCOS or oligomenorrhea but still doesn’t do well on a high-carbohydrate diet? It’s not uncommon at all for people to believe this is the case, but not many people have objective data to base this feeling on. So, how can you test if a higher-fat diet truly would be better for you?

How to Systematically Test Your Keto Diet Tolerance

In an ideal world, you could simply go get some blood tests done to determine your insulin sensitivity, but that is not a typical option for many people. And even then, if a doctor finds you to be insulin resistant, the typical recommendations are to lose some weight, do some resistance training, and get active. Well, if you are reading this text you are probably already taking care of all of those things. So if you get that diagnosis, you’re left with no solution according to the doctor.

So beyond going to the lab, I think an even better way to test your response to a higher-fat, lower-carbohydrate diet would be to run some off-season testing and data collection on yourself. I would recommend taking about a month to consume a 40% fat diet, with the same protein and calories that you have normally been consuming. This would simply be changing the carb-to-fat ratio and nothing more.

Throughout this month, write down and record a 1 to 10 rating on mood, energy, and training quality each day. Mood and energy are pretty straightforward to define, but I’d like to clarify that gym quality is different than gym performance. We are not looking at your program, volume, or poundage of weights lifted (you can and should track this as well, but only if you keep your training approach broadly the same so you can compare like-to-like). Rather, this is more about how you perceive your overall effort and mental state during the day’s training. After a month of tracking mood, energy, and gym quality, take an average score of those ratings.

When that month is complete, repeat the process for another month while consuming a 20% fat diet and keeping calories and protein the same. But you aren’t done yet! If you really want to bring the scientific method into your assessment, I would recommend running this trial a second time, making this whole process a 4-month commitment. If the outcome is repeatable, you can be much more sure it wasn’t some other factor outside of your diet that influenced your scores. At the conclusion, you’ll be able to see if your ratings were higher for one diet or the other both times, and you’ll have your answer.

This might seem like a big hassle to find out whether you do better on a higher-fat or higher-carb diet, but in the off-season, it’s definitely worth it. Also, what’s stopping you? Keeping your energy surplus size, protein intake and training the same (while of course still trying to progress) for four months is not unreasonable. So do it, learn more about yourself! If you see a big difference in these ratings from your 40% fat months and your 20% fat months, you might be able to conclude that a higher-fat diet is something for you to stick to in the long term. Also, put it in perspective, if you plan on lifting weights and trying to improve your body composition for the rest of your life while you’re able (which if you’re reading this book I hope you are), then four months is just a drop in the bucket!

For the latter two, adjust the load on the next set. A good rule of thumb is to adjust the weight by ~4% for every rep off target [8]. So, if you were off by 2 RIR, increase or decrease the load by ~8% on the next set.

If you have found this helpful, you might be pleased to know it is just a small section taken from our best-selling Muscle and Strength Pyramid books.

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