Fact-Checking Mike Mentzer’s Diet Advice

Written By: Jeremy Fox, CNC, CPTPublished: February 2, 2024

Mike Mentzer was a renowned 1970s bodybuilder and a staunch proponent of High-Intensity Training. He extended his philosophies beyond the gym to encompass nutrition based on his own research and personal experience.

However, his training and diet philosophies have faced criticism in recent years as they do not always align with current scientific evidence. As a certified nutrition coach, my aim in this article is to separate the facts from the myths regarding Mike Mentzer’s dietary advice.

Mike Mentzer Diet Philosophies

Throughout his career, Mentzer shared his insights on nutrition through various lectures and interviews. I reviewed hours of audio to summarize Mike Mentzer’s nutrition principles. Then, I fact-checked them against current clinical studies to determine which advice is substantiated and which is not supported by science.

Mike Mentzer’s Diet Philosophy

Mike Mentzer believed one must focus on intense resistance training before considering any diet plan. He argued that even the best diet will not result in muscle growth unless coupled with optimal training.

Mentzer also criticized the irrational overeating often associated with bodybuilding diets and advised a more rational approach based on the actual needs of the body.

“Training beyond need is overtraining; consuming nutrients beyond need is overeating.” -Mike Mentzer.

Mike Mentzer’s diet plan was formulated around gaining 10 pounds of muscle mass in one year without gaining excess fat. The plan focuses on determining the body’s individual energy and nutritional needs.

Determining Calorie Needs

The first step in the Mike Mentzer diet plan is determining your maintenance calories. This means figuring out how much you need to eat to maintain weight. Mentzer recommended keeping a food journal for 3-5 days while tracking your weight.

You have found your maintenance calories if your weight stays the same during those three days. However, if your weight goes up or down, it indicates that you are either over or under your maintenance target. Based on this information, Mentzer used simple logic to determine the calories required for muscle growth or fat loss.

In many of his lectures, Mentzer highlighted that one pound of muscle contains about 600 calories. Therefore, building 10 pounds of muscle in a year requires 6,000 calories or just 16 extra calories per day.

Similarly, Mentzer often cited that one pound of fat contains 3,500 calories. So, if you reduce your daily calorie intake by up to 1,000 calories below your maintenance need, you will create a 7,000-calorie weekly deficit, resulting in a loss of 2 pounds of fat per week.

Mike Mentzer Diet Lecture

How Much Protein?

Mike Mentzer frequently pointed out bodybuilder’s obsession with eating more protein. However, his ideology was the opposite and stressed that one does not need to overemphasize protein in one’s diet.

Mentzer’s reasoning behind protein intake goes back to his calculation that you only need 16 extra calories per day. Since muscle tissue is comprised mainly of water and only about 1/4 protein, he suggested that only four extra calories per day should come from protein.

It just so happens that there are four calories per gram of protein. So Mentzer contended that a bodybuilder only requires 1 gram of protein above maintenance to build 10 pounds of muscle per year.

Macronutrient Ratios

Mike Mentzer was a proponent of a high-carb diet and recommended that most of your daily calories come from carbohydrates. He based this on conventional wisdom that weight training burns sugar, and carbohydrates are the most efficient fuel for intense workouts.

Mentzer’s suggested macronutrient ratio for bodybuilding was 60 percent carbohydrates, 25 percent protein, and 15 percent fat. This would generally be considered a relatively high-carb and high-protein diet. At the same time, the dietary fat intake is on the low end of typical recommendations.

Mike Mentzer Macros

  • 60% Carbs
  • 25% Protein
  • 15% Carbs

Mentzer recommended scaling all macronutrients equally when raising or lowering caloric intake for specific bodybuilding goals. In other words, he proposed maintaining the same approximate macronutrient ratio irrespective of your training goal.

Food Choices

Mike Mentzer’s approach was also based on practicality. He expressed that all a person needs to concern themselves with is a well-balanced diet providing all the nutrients their body needs.

​His idea of a well-balanced diet was mainly consuming whole foods like fresh fruit and vegetables, lean meat like chicken breasts, and whole grains like rice and oats, with a limited amount of healthy fats.

However, Mike was also a realist and was perhaps one of the earliest adopters of flexible dieting, where junk food is permitted in moderation. He admits to consuming pancakes and ice cream daily leading up to the 1979 Mr. Olympia contest while consuming 200 grams of carbs per day.

Mike Mentzer Diet Advice

Dietary Supplements

Mike Mentzer was conservative regarding the use of dietary supplements. He saw them as largely unnecessary most of the time and believed commercial interests were the primary driver behind the rise in supplement use.

Mentzer’s approach was guided by the principle that the body absorbs only the required nutrients and nothing beyond that threshold. According to his understanding, excess supplementation offered no additional benefits.

Mentzer’s intake of supplements was strategic and limited only to times when he was concerned with not getting enough micronutrients, such as the calorie-restricted periods leading up to competitions.

Key points of Mentzer’s perspectives on supplements:

  • Situational: Only used them sparingly and when in a caloric deficit.
  • Essentials: Concentrate on micronutrients during critical times.
  • Economical: Don’t waste money on a vast array of supplements.
Mike Mentzer Dietary Supplements

Mike Mentzer Diet Plan Example

In practice, Mike Mentzer advised his clients to establish their maintenance calories. Then, he would have them add 300-500 calories daily to gain muscle or subtract 300-500 calories daily to lose fat.

For example, if you determine your maintenance needs to be 2,500 calories daily, you might consume 3,000 calories each day to gain muscle. Of those calories, 60% should be from carbs, 25% from protein, and the rest from fats.

That comes out to 1,800 calories from carbs, 750 from protein, and 450 from fat. ​Since carbs and protein have 4 calories per gram and fat has 9 calories per gram, we can determine your macronutrient targets in grams, as shown below.

Mike Mentzer Nutrition Example

  • ​Calories – 3,000
  • Carbs – 450 grams
  • Protein – 188 grams
  • Fat – 50 grams

After a week or two, you would assess your weight and strength level, then adjust calories as needed.

Fact-Checking Mentzer’s Diet Advice

Mike Mentzer is often seen as a credible source of information on bodybuilding and nutrition due to his impressive physique and achievements in the field. However, it’s important to note that his views are based on research that is now decades old and may not be relevant today.

Just because Mike Mentzer’s nutrition advice is logical, that doesn’t make it factual.

Therefore, it’s essential to verify Mentzer’s diet assertions with modern-day science and nutritional advancements. When I looked into Mentzer’s claims, I found that much of his advice was either slightly inaccurate or completely incorrect.

The table below shows which of Mentzer’s claims are substantiated by scientific research.

Table 1. Mike Mentzer Nutrition Claims vs Science
Claim Verdict Evidence
1 lb of muscle contains 600 calories False Muscle is about 800 cals/lb*
Gaining 1 lb of muscle requires a 600-calorie surplus False Metabolic processes would require about 2,140 cals*
1 g of protein beyond daily need builds muscle Unsubstantiated No evidence to support this
1 lb of fat contains 3,500 calories Supported Fat is about 3,700 cals/lb*
Losing 1 lb of fat requires a 3,500 calorie deficit Oversimplification Fat loss is not linear*

Some of Mike Mentzer’s boldest claims about bodybuilding nutrition were based on an oversimplification of muscle and fat energy densities. As a result, his rants about prescribing daily needs down to a single calorie don’t hold up to even mild scrutiny.

Trying to get within 16 calories or 1 gram of your target every single day would be impractical even with today’s accurate calorie-tracking apps!

In reality, metabolic processes that build or break down tissue also require energy. Menzer seemed to be somewhat aware of this as he suggested tripling his original numbers to account for possible metabolic demands.

Current research has also shown that weight loss and weight gain are not exclusively fat or muscle. Changes in metabolic rate also occur with body composition changes. Therefore, tissue loss and gain are not linear processes that can be predicted with simple algebra. 

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That being said, there are many grains of truth in Mentzer’s practical application of nutrition guidelines. For example, his foundation of a well-balanced diet and training program are still solid today.

In addition, his assertion that bodybuilders are preoccupied with protein is also very accurate. Most bodybuilders consume 1-2 grams of protein per pound of body weight, while no evidence suggests going higher than 0.83 grams per pound.

Mentzer’s recommendation of getting 25% of your calories from protein still constitutes a high-protein diet but typically won’t have you eating more than 1 gram of protein per pound, as long as your calorie target is within reason.

Bodybuilding Nutritionist’s Final Thoughts

Mike Mentzer was a pioneer in training and nutrition, and his methods were vastly different from the conventional wisdom of his time. He was a philosophical thinker who approached everything he did with reason and logic.

However, Mentzer was also highly competitive and sometimes had an overly strong opinion that his way was the only way. In my view, his diet lectures were more about showcasing his intellectual prowess in front of an audience and his peers.

At the same time, Mentzer was ahead of his time when he pointed out that people don’t need to take extreme measures with their diet to build muscle and lose fat. He believed moderate diet adjustments and time were vital to building a muscular physique.

Overall, Mentzer’s dietary advice is based on sound principles of nutrition. But I hope I’ve shown you that even the best bodybuilders are not always 100% accurate with their advice. So always keep a healthy skepticism and do your own fact-checking research!

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