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Should Training Determine the Diet or Vice Versa?

There are a lot of different ways to train.  And there are a lot of different ways to diet for fat loss.  In many cases, specific forms of training combine well with specific forms of dieting.     But in many others they do not and a given form of training will simply not be compatible with a specific approach to fat loss.   In that situation, the trainee is faced with the question of whether their training should determine the diet they use or vice versa?

When Does the Training Determine the Diet?

The first situation, when the training determines the diet, occurs when someone’s training program is either very specifically set up or simply cannot be changed.    In other cases, trainees can’t change their weight training program or simply don’t want to. 

Perhaps it’s a program they know works for them.  Perhaps it’s simply set up in a specific way in terms of the days per week they are supposed to train or the specific split routine that is being used.

So consider someone who trains on Monday, Tuesday, Thursday and Friday, perhaps on an upper/lower split routine.   A dietary approach such as Alternate Day Fasting (ADF) which alternates days of the week with very low and maintenance calorie would not work due to the fact that one or two of the low-calories days would fall on training days.

Certainly a calorie cycling approach with 2-3 lower calorie/carb days might be workable.  In this case, those days would be on the non-training days of the week.   So this is a situation where the training will determine the diet.

In contrast, someone lifting on Monday, Wednesday and Friday or Tuesday, Thursday and Saturday could make such an approach work.  They would simply put the “fasting” days of the ADF approach on their non-training days and eat “normally/at maintenance” no the training days.  The training and diet are now compatible.

Another situation would be one where someone is performing a lot of high-intensity training.  In this situation, a very low-carbohydrate/ketogenic diet for fat loss would be a very bad choice as it would be unable to sustain high-intensity exercise performance.   However, depending on how the weekly training was set up, some type of cyclical or targeted ketogenic diet might be workable.  In either case, this is a situation where the training determines the diet which can or cannot be used.

In the case of many types of sports training, the nearly daily intense training almost mandates that a moderate or high-carbohydrate approach be taken as this is the only way to sustain performance.  Almost no other dietary approach would be appropriate under those conditions.

I’m sure readers can come up with more situations like this.  Essentially any time that the trainee either can’t or won’t change their training structure will be one where the training determines the diet that can or should be used.      If a specific dietary approach to fat loss is not consistent with maintaining performance or optimizing results, it can’t be used.

In this case, the training determines the diet.

When Does the Diet Determine the Training?

In other situations, someone who wants to follow a specific diet will find that it impacts on what type of training can or should be done.

I mentioned one example in reverse above.  Say someone wants to follow an ADF approach to dieting, where alternate days of “fasting” (really 25% of maintenance calories) and normal eating are done during the week.  In the sense that training and dieting approaches work best when they are synchronized, this would tend to force a training structure

Someone choosing an Intermittent Caloric Restriction (ICR) approach, where the number of “fasting” and maintenance days are a more flexibly programmed has more leeway in this regard.  However, once they have chosen the number of diet days (typically 3-4) and maintenance days (4-3) and what days they will fall on, that will constrain their training to certain days of the week.  So if they choose 3 diet days on Monday, Thursday and Sunday, that would ideally require a training structure of Tuesday, Wednesday, Friday and Sunday.

Cyclical diet structures, which typically alternate 4-5 days of lowered calories and carbohydrates with 2-3 days in a row of carbohydrate tend to constrain training as well, at least to some degree.  An extreme example of this is my own Ultimate Diet 2.0.   This is an extremely specifically structured diet revolving around three different types of eating and training and each day of eating and training is placed specifically to optimize the results.

Really this is a place where the diet determines the training and the training determine the diet since it was designed as such.  But every so often people ask if the diet structure can be used with a different type of training and the answer is generally no. There are ways to structure training within the weekly diet structure to make the diet work but even here this is a situation where the specifics of the diet itself determine what training can or should be done and when.

A bigger issue occurs when people can’t train on the appropriate days of the week that UD2 requires.  In this case, the training and diet days no longer synchronize optimally and a different dietary approach should be chosen.  The Ultimate Diet 2.0 diet determines the optimal training structure and any other training structure will determine that a different diet should be chosen.

People who want to follow low- or very-low carbohydrate/ketogenic diets also tend to be limited in their training.  The diets cannot generally support very large amounts of high intensity activity although low-intensity exercise is rarely impaired.  Once again, the diet determines the training that can be done. As I mentioned above, modified ketogenic diets do exist to help avoid this problem.

A final example is my own  Rapid Fat Loss Handbook (RFL), a very low-calorie, very-low carbohydrate, very-low fat diet that is meant to generate extreme results in a short period of time.  The nature of the diet only allows for relatively small amounts of training to be done or considered.  Two to three short weight training workouts and a small amount of low-intensity cardio are the most that can be done.  The diet mandates it.

And occasionally I will get asked how to make it work for those athletes or trainees who must or want to do more training than I recommend.  And my answer is to tell them to pick another diet.  The nature of the RFL diet determine what training can be done.  If a different type of training is required or desired, a different diet must be chosen.

In this situation, the diet determines the training.


The point of this short article is that there are time when the training will determine the diet and others when the diet will determine the training.  The first situation occurs when a given style of structure of training is either required by the trainee or they simply want to do it for one reason or another.  In that case, certain dietary approaches will be eliminated and others will more or less be required.  The training determines the diet.

The second situation occurs when someone wants to follow a specific dietary approach.  Depending on how it is set up, the type of training that can, should or even must be done may be constrained in some way.  In that case, the diet determines the training.

What ultimately can’t be done is for the trainee to try to put a round peg into a square hole.  You can’t force a diet into a training structure that won’t accommodate it any more than you can force a training structure into a diet won’t allow it.

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11 thoughts on “Should Training Determine the Diet or Vice Versa?

  1. Excellent article, Lyle. In my humble opinion, the RFL is the best crash diet out there. However, I developed some bloating in my lower belly from the diet.

  2. Small correction:

    Does the Training Determine the Diet or the Diet Determing the Training?

    Should probably read:

    Does the Training Determine the Diet or the Diet Determine the Training?

  3. Hey Lyle, thanks for the article.

    I’v done a fairly extreme cutting diet for the Summer in the past and lost a load of fat in 1 month. I was at almost a 1000kcal daily deficit, training heavy 3 times a week and doing conditioning sessions on my off days. It was tiring, but I maintained my strength. Can some people handle much more training whilst dieting than others? I consider myself fairly fit and feel as though I can do a lot more besides just the three lifting sessions while dieting.

  4. Excellent article as usual, Lyle. I see this type of thing all too frequently both with kick boxing and Crossfit type training. In both situations, low carb usually doesn’t work. On one case because of endurance requirements and on the other due to intensity requirements. A big part of the Paleo community seems in love with Crossfit because guys like Rob Wolff advocate it but there’s a difference between being Paleo low carb and Paleo high carb. Most people remain Paleo low carb and struggle to keep up with the intensity and fail to recover fast enough after the workouts. Just my 2c.

  5. ” what the diet can support ” (from your article above)

    In my mind this portion of your statement is a highly relevant point, that goes right to the heart of the matter. I tend to think that making this determination is a highly individualized process. I found during what has amounted to a 2 year experiment in which I lost 70lbs and am working to wards going from 11% to 7% body fat, that in order to arrive at my own personal “what the diet can support” I have relied on internal instincts and best educated intuition.

    Even the fitness professionals who I respect and admire most can’t formulate or arrive at this very personal state of energy-life-exercise-dietary balance for me. I have to do it! I can listen to those who know more than me about the business of health, fat loss and nutrition, but only I can and must be responsible for my energy states and the results thereof.

    Again Lyle, thanks for another balanced and insightful article.
    Greatly admire your work with the dogs by the way.

    Scott Murphy

  6. Sweet and short, great article, Lyle! 🙂

  7. Lyle,

    Do you have any experience with clients/athletes to whom a high protein diet is contraindicated? I had been following your advice RE: diet set up, and then had blood work done and they found elevated liver enzymes (AST & ALT) and thought I had liver damage or hepatitis. The only warning signs My doctor came up with were high protein intake, intense exercise, and past alcoholism. I stopped the high protein diet, and didn’t exercise the day of the next tests. Levels are back to normal, ultrasound shows no liver damage (whew!).

    I’m now scared of high protein, but worry that my intense training while dieting requires it. Any thoughts, or experiences?

    On a related note: My hometown (Kitchener, Ontario, Canada) just lost a all star Hockey player who died due to liver problems stemming from a high protein diet and a LACK of a liver enzyme.

  8. Pesonal experience, very little. Join the support forums:

    ping David Cohen. He’ll know.

  9. Thanks Lyle!

  10. I can say that this is an excellent article you shared to us. Yeah! I believe also that the RFL is the best crash diet out there now. Aside from this, I guess the diet determined the training how can you give ideas on the process of diet if you don’t know how.

  11. I train 7 days a week, but I have structured a diet around that, where I have one very low carb/high fat day with a deficit in total daily calories of 20%.

    I just want to say your book UD2 has helped me gain a better understanding of how to structure a sound diet and how different hormones can effect your results. Thanks to you I feel like im eating a GODLIKE amount of carbs and the fat is still stripping off my body, currently I am at around 11-12% bodyfat. Cant wait to read more of your books!

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