What Makes A Diet Work?

Nutrition is arguably the most misunderstood variable when it comes to achieving your body composition goals. With so much conflicting information floating around the web, through fitness magazines and even through some peer reviewed research; you often find yourself wondering "Which nutritional strategy is right for me?". In this post I'll discuss and compare three of the most popular types of diets used today; the basic mechanism as to why they work and how to properly implement nutritional strategies to work for you in the long term.

What Makes A Diet Work?

Before delving into the various types of diets; we must first understand how the manipulation of different variables can affect fat loss and body recomposition goals. Understanding that you may need to consume a certain amount of calories for the day to maintain your weight; you know that logically, by eating within a deficit of calories over a period of time will eventually lead to weight loss. Someone who may required 2500 calories for the day to maintain their energy balance will eventually lose weight if he consumes 2300-2400 calories per day consistently; whereas eating in excess of that will lead to weight gain. It is a definite that understanding your total daily energy expenditure(TDEE) will always be the most relevant factor when it comes weight gain/loss.

When it comes to achieving your body composition goals; eating in an excess or deficit of calories becomes secondary to macronutrient partitioning. This is where the ratios of protein/carbohydrates/fat play a role on how much lean muscle you build while minimizing fat gain; as well as how much fat you lose whilst maintaining lean body mass. Simply put, following a diet very low in protein over a period of time will eventually lead to a loss of  lean body mass regardless of eating in a caloric deficit/surplus whereas following a diet high in protein while eating in a caloric deficit may allow you to maintain(or gain muscle as a beginner) while also facilitating fat loss. This is because protein has a muscle sparing effect and is the main driver of muscle growth. The effectiveness of a diet is usually measured on the basis that it is very high in protein while also calorically restricted; where dietary fat and/or carbohydrates may be the manipulative variables. When it comes to most of our popular diets, the common trend you may find is that authors may encourage you to limit your carbohydrate intake while increasing your dietary fat intake to moderate/high amounts. This is primarily because a moderate-high dietary fat intake helps to facilitate the optimization of hormonal function which will result in increased fat loss and muscle retention. 

I have limited this article to three popular diets as they can be easily representative of the broader population of dietary systems/strategies. That is; a dietary protocol may either encourage macronutrient restriction, time restricted eating/fasting or altering your selection of food entirely. With each of the following dietary strategies; I'll use a practical example of each to explain how fat loss and body recomposition is made possible. 

Low Carb Diets

Whether it is the atkins diet, meat based paleo diet, or ketogenic diet; the basic mechanism for fat loss remains essentially the same. Every variation to a low carbohydrate diet demands that you severely restrict carbohydrates for extended periods. The rationale behind this strategy is that by eliminating carbohydrates and increasing your dietary fat and protein intake; your body will be forced to use your fat stores as a form of energy rather than glycogen(which is produced by glucose). When we restrict carbohydrates; the primary source of energy your body will eventually become ketone adapted. This occurs when the body preferentially uses energy molecules known as 'ketones' instead of glucose to fuel physical activity and brain function. It is speculated that ethnic groups that have adapted to colder climates may do well on a high fat/low carbohydrate diet and sustain it for long periods at a time. This could possibly be because of the lack of vegetation in very cold regions.

A low carbohydrate diet comprises large portions of meat, nuts, oils and dairy while restricting carbohydrates

Why Do Low Carbohydrate Diets Work

It all goes back to the single most relevant factor of weight loss; a caloric deficit over extended periods of time. When switching from a regular eating pattern to a low carbohydrate diet; you're doing essentially that; restricting carbohydrates altogether. When you switch from following a grain based diet to one rich in polyunsaturated fats; you may inadvertently be decreasing your daily caloric intake while also maximizing your protein intake to create a muscle sparing effect. 

Why A Low Carbohydrate Diet May Not Work

A low carbohydrate diet may not work for someone who doesn't understand the basic mechanism as to why diets work. Some people who switch over to a low carbohydrate diet may consume dietary fats in excessively large portions which will inevitably result in a surplus of calories. Regardless of adhering to a carbohydrate restricted diet and macronutrient partitioning; the single most important factor of weight loss and body recomposition is still relevant; that is a surplus of calories will lead to weight gain and a deficit will ignite weight loss. In the context of today's society a low carbohydrate diet may also not be ideal for sustainable long term progress as it may be inflexible for most people. If you have performance based or body composition goals, a low carbohydrate diet is unnecessary once you understand the basic mechanisms of muscle gain/fat loss. 

Intermittent Fasting

Where a low carbohydrate diet is an example of utilizing nutrient restriction strategies to achieve weight/fat loss, intermittent fasting encourages time restricted eating patterns  to achieve similar goals. Ori Holfmelker; author of "The Warrior Diet" argued that by purposefully fasting/undergoing periods of under-eating followed by short periods of over-feeding we would be able to effectively maximize the production of both hormones associated with anabolism(muscle building) and catabolism(fat loss) in absence of the long term negative effects associated with each; such as muscle loss through long term calorie restriction or fat gain through extended periods of over-eating. Hofmelker argued that by fasting upwards of 20 hours and over-eating for 4-6 hours we effectively emulate the way our primal ancestors had eaten for millions of years, and this nutrition approach would be optimal for not only achieving your desired body composition but also yields significant health benefits over a conventional 3-5 meals a day diet. Since the publication of the Warrior diet; different variations of intermittent fasting had emerged; Brad Pilon's Eat-Stop-Eat which employed fasting for 16 hours followed by an 8 hour eating window popularized the concept and now it is seen by many as the holy grail of diets as you can be as flexible as you like with your food selection.

This is what a 16 hour fast followed by an 8 hour eating window looks like.

Why Does Intermittent Fasting Work

Intermittent Fasting works for the same core reason a low carbohydrate diet does. That is; by restricting your eating window to 4-8 hours you are much more likely to consume less total calories while eating til satiety than if you were to have more frequent meals throughout the day. When you follow unregimented eating patterns where there is no regulation to meal frequency and portions, without regards for macronutrient ratios it becomes very easy to over-eat for extended periods of time. Intermittent Fasting simply provides structure and regulation to your nutritional habits and it may provide more flexibility than a conventional diet depending on your personal preferences and time constraints. You do also find that most authors who encourage time restricted eating will also employ a diet that is rich in protein in order to make intermittent fasting an effective solution for your fat loss goals.

Why Intermittent Fasting May Not Work

Although there is some research to suggest that the benefits of intermittent fasting may possibly go beyond a calories in vs calories out equation; you would find that these benefits are so minor that they become ultimately irrelevant when you consider some of the more important variables such as being able to meet your macronutrient targets. It is also worthy to note that much of the research was done primarily using animal models. Time restricted eating may work against you if you require more time between meals to meet your macronutrient targets or if your schedule does not allow you to fit all your meals within a set eating window.  Some people believe that the magic of intermittent fasting lies within the eating window and as a result fail to achieve their body composition goals. They may eat the same portions of food as they did before without respecting the calories in vs. calories out rule; resulting in stagnation.

Vegan Based/Paleo Diets

Although both systems differ tremendously, I have placed them within the same category on the basis that they represent diets based around food selection rather than macronutrient or time restriction; the types of food you eat on each diet is limited based on the approach you use. Some argue that a vegan based diet is ideal for weight loss on the basis that you effectively eliminate fattier cuts of meat from your diet while maximizing nutrient rich food such as grains, fruit, vegetables, nuts and seeds. On the opposite end of the spectrum one may argue that a paleo diet is ideal because you are able to effectively maximize your intake of protein and healthy fats while eliminating refined carbohydrates and grains altogether which may reflect positive changes in body composition and fat loss. 

Why Does Food Selection Strategies Work

Again, using an example of an individual who switches from unregimented eating patterns without regard for meal portions or frequency, each system provides some structure to the types of food they eat. In the case of a vegan diet where it is generally more difficult to find non-meat based foods that are significantly higher in dietary fats it becomes very easy to eat within a deficit of calories as each gram of fat yields a total of 9 calories; as opposed to protein and carbohydrates that yield 4 calories per gram each. This is particularly true when it comes to raw food based vegan and juicing diets where the use of oil is minimized. In the case of a paleo diet the opposite holds true in that the adherent may actually look to maximize his/her dietary fat intake while minimizing or regulating their carbohydrate intake by eliminating grains and other refined carbohydrates. A traditional paleo diet encourages the adherent to eat fruits in moderation as the argument is that in ancient times fruits were scarcely available and seasonal and therefore we were less adapted to consume fruits in large portions. This is highly debatable as the most relevant factor to note is that positive changes in body composition is reflective of a surplus in protein and a deficit in total calories over extended periods.

Why Food Selection Strategies May  Not Work

A paleo diet may lose effectiveness for the same reasons a low carbohydrate diet would. Someone who fails to meet their body composition goals on a paleo based diet may often find that they are over-consuming food rich in saturated fat; which would easily push you over your TDEE. It is also argued that there is no clear indication of what types of foods may classify as being 'paleo'; which may create some confusion amongst those who choose to follow paleo style eating in an attempt to achieve their body composition goals; there is also evidence to suggest that the inclusion of carbohydrates was essential for human brain development. 

There are so many different variations to a vegan based diet that to measure all the reasons why they may not work is beyond the scope of this article; however one of the biggest mistakes a vegan dieter may make is having an inadequate protein intake and although weight loss is possible; the dieter may also experience a degradation in lean body mass. In the case of vegan diets, this is not a limitation as protein needs can be met as a vegan by consuming plant based protein sources such as lentils and beans; as well as nuts, seeds and various grains such as quinoa.  The introduction of vegan based protein supplements may also assist in meeting your protein needs on a vegan based diet. 

What You Should Do

If a diet or nutritional approach does not allow you to remain consistent for long periods without the degradation of health; it is not ideal for achieving your body composition goals. A good nutrition plan is flexible, goal focused and most importantly; sustainable. It must allow you to eat any variation of food that you choose rather than changing your selection of foods entirely. Instead you should be able to create modifications to your diet and consume foods that are cost efficient and convenient to you.

In order to ensure that you are on the right track in organizing a well balanced nutrition plan; ensure the following:

-Your protein intake is adequate; at least 1g per pound of lean body mass each day. This means that if you are 200lbs and your lean body mass is 150lbs; your body requires at least 150g of protein a day.

-Ensure that at least 20-35% of your calories come from dietary fat. This means that if it is that you require 2000 total calories; then at least 400 cals should come from dietary fats. 

-Understand that your carbohydrate intake is the most variable and you may use it to add flexibility to your diet; in that you can allow yourself to under-consume carboohydrates with some margin of error considering that your protein and fat needs are met.

-Ensure that your micronutrient needs are met by consuming an adequate amount of fruits and vegetables. An omega 3 supplement is necessary as it may be impractical to meet your omega 3 needs through whole food sources.

-Ensure that your total calories consumed reflects the goals that you are looking to achieve. A calorie deficit if your goal is to lose bodyfat, a caloric surplus if your primary goal is to build muscle.

Sources:

University of Chicago Press Journals. "Paleo diet: Big brains needed carbs: Importance of dietary carbohydrate in human evolution." ScienceDaily. ScienceDaily, 6 August 2015. <www.sciencedaily.com/releases/2015/08/150806133148.htm>.

Manninen, Anssi H. “Very-Low-Carbohydrate Diets and Preservation of Muscle Mass.” Nutrition & Metabolism 3 (2006): 9. PMC. Web. 17 Feb. 2016.

Brandhorst, Sebastian et al. "A Periodic Diet that Mimics Fasting Promotes Multi-System Regneration, Enhanced Cognitive Performance, and Healthspan." Cell Metabolism, Volume 22, Issue 1, 86-89

Volek, J. S., Kraemer, W. J., Bush, J. A., Incledon, T., & Boetes, M. (1997). Testosterone and cortisol in relationship to dietary nutrients and resistance exercise. Journal of Applied Physiology, 82(1), 49–54. Retrieved from http://jap.physiology.org/content/82/1/49.abstract