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5 Popular Diets Reviewed – What’s the Best Diet For Fat Loss?

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With many different types of diets available, it’s often debated what the best fat loss diet really is?

Regardless of which dieting style you choose, energy balance (or calories in vs. calories out) almost always reigns supreme; however, each diet does have pros and cons.

The trick is to find a diet that will allow you to create a negative energy balance with minimal effort and maximal results, right? Despite what uneducated gurus and trainers may tell you online, there is no BEST diet, but there are better diets and, most importantly, more suitable diets for YOU, as an individual.

In this article, I’ll discuss some of the most popular types of diets including why they are beneficial and other information to keep in mind when choosing the right diet for YOU, based on your food choices, metabolism, lifestyle and goals!

1. Traditional Calorie Restriction / Clean Eating Pros & Cons

Traditional calorie restriction via “clean eating” is one of the most popular styles of dieting that has been around for decades.

People turn to this style of eating when attempting to lose weight and body fat, often under the impression that choosing clean foods will result in weight loss.

Truth be told, clean eating is really a catch-all term for increasing the amount of quality, nutrient dense foods in your diet while limiting consumption of processed foods. Now, that’s a pretty good basic rule to follow, don’t you agree?

When people switch to a clean eating dieting style, they often significantly increase the quality of food being eaten. Additionally, most of these types of foods are nutritionally dense, meaning they provide a large volume and satiating effects, while being low in calories (1, 2).

Further, most people often under consume protein and fiber; both of which can help you feel fuller for longer (3, 4, 5).

Even more, studies have shown that consuming more protein directly increases your metabolic rate, potentially resulting in weight loss (6).

So success using this diet likely isn’t just attributable to clean eating per se, but is rather due to an increase in protein and fiber intake, along with a reduction of calories. Remember, ‘clean eating’ is just the vehicle, the driver is still a reduction in calories and an increase in protein.

While clean eating, and the subsequent restriction of calories, can certainly be a great choice, this style of eating is often taken to an extra and super restrictive level, leading to bingeing on foods often considered to be “unclean” or dirty.

In order to avoid this, the key point to remember is that you should follow the basic clean eating rules 80% of the time, BUT still allow yourself some ‘non clean’ food in moderation. When you do have a cheat meal or ‘non clean’ meal, do not freak out, just enjoy it then get back to work the next day.

Additionally, do not get mind-washed into thinking that all non clean food is bad; remember, you probably ate that daily for 20-30 years and it didn’t kill you. Yes, clean eating is great, but remain flexible and understand that the odd treat is perfectly fine.

Pros: Healthy, simple to follow (just don’t eat anything processed). Focuses on the staple foods (meat, fish, dairy, vegetables etc), quickly forces a calorie deficit.

Cons: Can be restrictive after some time, limits food intake. Hard to maintain on vacation, may lead to yo-yo dieting or binge eating.

2. Flexible Dieting or IIFYM Pros & Cons

Flexible Dieting or If It Fits Your Macros (IIFYM) is a dieting style that has taken the fitness world by storm.

The interesting thing about flexible dieting is that it places an emphasis on macronutrients or tracking macros rather than simply counting calories or the types of foods you are eating.

Macronutrients (protein, carbohydrate and fat) have a caloric content that makes it easy to track on a daily basis. For every 1 gram of protein, carbohydrate and fat you get 4, 4, and 9 calories, respectively.

Since weight loss is primarily dependent on consuming less calories than expended, proponents of this diet argue that by focusing on consuming a certain ratio of macronutrients rather than specifically the types of food you’re consuming, you can eat foods you enjoy while tracking the macro and calorie amount. Based on the science, they are exactly right. Even though food quality IS important long term, ultimately calories and macros are key for body composition and fat loss.

Flexible dieting has become so popular as it is often less restrictive than other types of dieting and places a focus on the macronutrients, rather than the food itself. This allows for you to still eat a candy bar, or some pasta, once per day but to still lose weight effectively as everything is controlled in moderation.

Because clean eaters and the fitness world often do 4000 calorie binges, I actually like this diet if it is used sensibly. By this, I mean you still focus on clean foods 80% of the time, tracking calories and macro intake then get a small moderation of ‘bad food’ without freaking out or feeling like you failed.

However, flexible dieting is not without its downsides. The notion of being able to consume anything you want, as long as it fits within your macro and calorie budget is now sometimes taken out of context, with people consuming 80% bad food and 20% good food, the opposite of what we want.

Bear in mind that if you decide to use this dieting approach, you’ll need to use a calorie and macronutrient tracker or food log, to ensure that you are hitting your macro amounts and consuming the appropriate amount of calories for your goal. Although it can be learned easily, this is another downside for a total beginner, so can be overwhelming at first.

You can learn more about macros and tracking in my Guide to Macro and Calorie Tracking Blog Post

Pros: Allows flexibility on a daily basis, pinpoints macros and calories which are key for fat loss or body comp. Teaches people to track food and learn the nutritional values of most foods.

Cons: Often taken too far and people eat bad food daily, consuming less healthy whole foods. Can be overwhelming for beginners or those that have little knowledge of calories/macros/nutritional labels.

3. Intermittent Fasting Pros & Cons

Intermittent fasting comes in many different forms but is classified by spending a portion of the day fasting or not consuming calories, followed by a period of eating.

Types of intermittent fasting range from fasting for 12-16 hours, to fasting for almost entire days, every other day (otherwise known as alternate-day fasting). Proponents of intermittent fasting claim that by fasting for a period of time during the day, you’ll be able to drop body fat with ease and have more flexibility in the evening.

Interestingly, research seems to corroborate this, as multiple studies have revealed the potential benefit of intermittent fasting for health and fat loss (7, 8).

As it turns out, by restricting the amount of time that you are eating, it becomes increasingly difficult to consume more calories than you expend, due to feelings of fullness and just lack of time. Remember, this is still the KEY drive. Again, intermittent fasting is the vehicle, but calorie reduction is the key driver of fat loss.

Despite its potential benefit, intermittent fasting can often be difficult for people due to the fasting period. Many people who are not used to fasting can get headaches, fatigue, low energy and some may binge eat later in the day as they are so hungry from the fast during the day.

While fasting will likely be difficult at first, anecdotal reports indicate that after about a week or so the body adjusts and it becomes easier. Just like anything, it takes time to adjust, especially if you’ve eaten breakfast for 20, 30 or 40 years!

Ultimately, fasting works great for some people but others may hate it. Try it out for 2-4 weeks before making a judgement. Also, remember you can just fast 1-2 days a week or whenever you like, there is no need to do it daily.

For example, I fast when I am on vacation or away and eating big meals at night. I also fast randomly if I have a super busy morning, then just eat more later in the day to make up for it. As you can see, it’s just another tool to allow flexibility and keep calorie intake down!

Pros: Allows for more flexibility in the day. Some people feel and function better in the day at work with less food. Easy to maintain for some people.

Cons: Some people feel horrible during the fasting period. Some people may also overeat because they are super hungry by the time the feeding window occurs.

4. The Ketogenic Diet Pros & Cons

The Keto or Ketogenic Diet places emphasis on consuming high fat, while restricting carbohydrate intake to very low with a moderate protein and vegetable intake.

In fact, in order to use the ketogenic diet, you’ll need to consume around 65-75% fat, 20-30% protein and roughly 5% carbohydrate or less! It basically eliminates all carbohydrate sources from the diet, even fruit.

The theory behind ketogenic dieting is that by consuming primarily fat and restricting carbohydrates, you force your body to preferentially metabolize fat and produce ketones, which have some unique health benefits.

In fact, many studies have indicated that the ketogenic diet is in fact quite effective at helping people metabolize fat and lose body weight. Additionally, one meta-analysis even indicated that using a ketogenic diet might be more effective than other low fat, calorie restrictive diets! (9, 10)

Despite its benefit, keep in mind that the ketogenic diet can be quite restrictive and only suitable for a specific group of people who are fine with cutting out carbs. In order to benefit from using keto, you’ll need to ensure that you’re consuming a large amount of fat, but restricting the other macronutrients for days and weeks. Unlike other diets above, you can’t just randomly use the ketogenic diet for one day. It needs to be maintained for weeks and months without fail or a ‘day off’ in order to gain any benefits.

Along with the long-term commitment and restriction,  the ketogenic diet is often associated with a transition period in which you can feel nauseous, tired and fatigued due to the high fat and low carbohydrate content. This period usually lasts around 2 weeks and then subsides. Finally, a ketogenic diet may not be optimal for muscle mass or sport. Sure, it can work, but if you are a high end athlete it’s likely not an optimal choice.

Pros: Great for fat loss and metabolic health. Great for those who love fatty foods and don’t like carbs. Also many people report better energy, skin, other health benefits.

Cons: Super restrictive, can be complex to restrict carbs (they are in almost everything!), may not be sustainable for lots of people. Not the best diet for optimal muscle mass growth or elite sports performance (though can still be ok, just not the best).

(Related: You can get full 7 Day Ketogenic Meal plans and workout plans in the Metabolic Advantage Diet).

5. Paleo Diet Pros & Cons

The Paleo diet is a popular diet placing an emphasis on whole and nutrient dense foods and basically teaches you to ‘eat like a caveman’.

The theory behind this diet is to return to our roots by avoiding processed foods while placing an emphasis on whole nutrient dense foods that we ate centuries ago, just as our ancestors did. This style of dieting is extremely similar to traditional, clean eating diets, but is often a bit more restrictive as some paleo eaters will even eliminate dairy and other whole foods.

While the Paleo diet can certainly be beneficial due to an increase in nutrient dense foods, and thus calorie restriction, it can often be very restrictive and difficult to adhere to.

Ultimately, it again is just forcing you to increase vegetables and protein intake, while also eliminating all bad food and most carbs. This is why people lose lots of weight; although some paleo eaters think it’s magical, as you now know, the key is still calorie restriction!

Pros: Very healthy, simple rules to follow (just don’t eat anything processed or that wasn’t around 100 years ago). Focuses on the staple foods (meat, fish, fruit, vegetables etc). Forces a calorie deficit quickly.

Cons: Can be restrictive after some time, limits certain foods 100% of that time (remember, balance is key). Hard to maintain on vacation, may lead to yo-yo dieting or binge eating when you get your first taste of chocolate or pizza again.

Bonus: The Rudy Approved Diet (Summary)

Of course, this is clearly the best possible diet for getting ripped and being super awesome (haha).

In summary, you’ve learned that each diet has its pros and cons. As you can see, all 5 diets have merit and are, in general, 5 of the better dieting methods in the world (hence why I selected them).

However, the staples of fat loss and human nutrition must be in place regardless. Once these are in place, you can then really just select any dieting method that you enjoy, or a mix of more than one. The staple points we master in all my plans and coaching are:

  • Consistency and enjoyment
  • High protein intake
  • Calorie intake tailored to your body, metabolism and goals (like we teach in the 90 day bikini plan )
  • High fiber and water intake
  • Focus on whole natural foods
  • Ability to achieve balance and have the odd bad food without freaking out
  • Mixed diet of fruits, vegetables, meats, fish, healthy fats and possibly healthy carbs (unless you are low-carb).

As you can see, there’s nothing overly magical and sexy like lots of people try to sell you. These are the basics you must master and will drive 95% of your success. Focus on these, then you can always throw in the odd fasting day, or IIFYM day, or a total paleo day where you eat 100% clean.

In summary, play around with all the diets and see which you love and find easiest to maintain. As long as the key points above are in place, then you should simply pick what you enjoy!

If you want a highly advanced carb cycling plan that gets a healthy balance between many of the diets above (without some of the negatives you can download the 7 day meal plans here).


  1. 1. Luscombe, N. D., Clifton, P. M., Noakes, M., Farnsworth, E., & Wittert, G. (2003). Effect of a high-protein, energy-restricted diet on weight loss and energy expenditure after weight stabilization in hyperinsulinemic subjects. International journal of obesity, 27(5), 582-590.
  2. 2. Veldhorst, M., Smeets, A. J. P. G., Soenen, S., Hochstenbach-Waelen, A., Hursel, R., Diepvens, K., … & Westerterp-Plantenga, M. (2008). Protein-induced satiety: effects and mechanisms of different proteins. Physiology & behavior, 94(2), 300-307.
  3. 3. Bolton, R. P., Heaton, K. W., & Burroughs, L. F. (1981). The role of dietary fiber in satiety, glucose, and insulin: studies with fruit and fruit juice. The American journal of clinical nutrition, 34(2), 211-217.
  4. 4. Cho, S. S., Case, I. L., & Nishi, S. (2009). Fiber and Satiety. Weight Control and Slimming Ingredients in Food Technology, 227.
  5. 5. Lefranc-Millot, C., Macioce, V., Guérin-Deremaux, L., Lee, A. W., & Cho, S. S. (2012). Fiber and Satiety. Dietary Fiber and Health, 83.
  6. 6. Westerterp, K. R. (2004). Diet induced thermogenesis. Nutrition & metabolism, 1(1), 5.
  7. 7. Moro, T., Tinsley, G., Bianco, A., Marcolin, G., Pacelli, Q. F., Battaglia, G., . . . Paoli, A. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine, 14(1). doi:10.1186/s12967-016-1044-0
  8. 8. Varady, K., Bhutani, S., Church, E., & Klempel, M. (2009). Short-term modified alternate-day fasting: A novel dietary strategy for weight loss and cardioprotection in obese adults. American Journal of Clinical Nutrition, 1138-1143.
  9. 9. Yancy, W. S., Olsen, M. K., Guyton, J. R., Bakst, R. P., & Westman, E. C. (2004). A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemiaA randomized, controlled trial. Annals of internal medicine, 140(10), 769-777.
  10. 10. Rauch, J. T., Silva, J. E., Lowery, R. P., McCleary, S. A., Shields, K. A., Ormes, J. A., … & D’agostino, D. P. (2014). The effects of ketogenic dieting on skeletal muscle and fat mass. Journal of the International Society of Sports Nutrition, 11(1), P40.

About the author


Rudy Mawer, MSc, CISSN

Rudy has a 1st class BSc in Exercise, Nutrition & Health and a Masters in Exercise & Nutrition Science from the University of Tampa. Rudy currently works as a Human Performance Researcher, Sports Nutritionist and Physique Coach. Over 7 years he has helped over 500 people around the world achieve long last physique transformations.

He now works closely with a variety of professional athletes and teams, including the NBA, USA Athletics, World Triathlon Gold Medalists, Hollywood Celebrities and IFBB Pro Bodybuilders. If you would like to get in contact or work with Rudy please contact him on social media.

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