Nowadays, fad diets seem to be everywhere: social media, magazine covers, bookstores, television. It's hard to step into a room at work without hearing someone talking about their new diet strategy as if they’ve found the one true pathway to success.

That’s well and good for them, but if everyone seems to feel that way about their diet plan, how do you know which diet is truly the best? From a paleo diet to a gluten-free diet, to a low-calorie diet, to a high-protein diet, to a low-fat diet, to a raw food diet, and a blood type diet (and everything else in between), it’s hard to know what will help you achieve a healthy lifestyle.

Every diet plan has its own strengths and weaknesses, and it’s important to know what to expect before making any drastic changes to your lifestyle. A few popular diet plans people can’t seem to stop talking about include:

• The Keto diet
• Intermittent fasting
• The Mediterranean diet
• Plant-based diets

When the dieting options seem unlimited, and everyone feels so attached to their own path, it becomes hard to get an objective view. Read on to get a straightforward overview of these four popular diets, as well as some of their pros and cons.

The Keto Diet 

The ketogenic diet, named after the state your body goes into when it processes fat into energy, involves a strict cutting of carbohydrates from the diet. It’s one example of the various low-carb diets that people follow. Those following a strict keto diet omit all bread and grain-based products, including pasta, rice, anything with whole grains, and bread. It also typically eliminates most processed foods.

Because carbohydrates, which are the body’s usual source of energy, are replaced by additional fat, the body turns to fat as its primary source of energy. Fans of this diet plan say that it helps them get slim without the starvation effects that come with many other diet plans.

Pros:

• Burns fat: By sending the body into a state of ketosis, this diet enables its followers to burn through larger amounts of fat without fasting.
• Regulates hunger: Proponents of this diet claim that it helps regulate their appetites, eliminating the desire to snack throughout the day.
• Highly popular: Because such a large number of people attempt this diet, it’s easy to find items in the grocery store labeled “keto-friendly.” While difficult to maintain, this diet may feel less isolating than others.

Cons:

• Only possible in the short term: Certain processes in your body require healthy carbohydrates to function, specifically your brain. Too much time on this diet can result in mood swings and problems focusing.
• Highly restrictive: Carbohydrates exist in almost all foods we eat. Strictly following this diet can be extremely limiting, requiring followers to make sacrifices that may feel extreme at times.
• Liver or kidney problems: Your liver and kidneys are responsible for processing fat and protein. A diet entirely dependent on these two macronutrients could stress those two organs, potentially creating a long-term problem. Anyone struggling with preexisting liver or kidney problems should never attempt this diet.
• Nutrient deficiencies: Following this diet requires you to cut out the majority of your intake of fruits and vegetables, which also happen to be the greatest source of most required nutrients.

Intermittent Fasting 

Intermittent fasting is less of a diet plan and more of an eating pattern. Followers of this diet choose extended periods of time during which they eat no food whatsoever, followed by shorter periods of time during which they eat whatever healthy food they desire. The idea behind this diet is that by creating fasting periods, you can force your body into ketosis and change your metabolic rate. Typically, you are eating fewer calories overall.

While everyone finds a pattern that works differently, one of the most popular patterns is 16:8, a schedule of 16 hours of fasting and eight hours of eating, known as the “eating window.” Someone under this easier “beginners’ pattern” would restrict all meals to the hours between 11 am and 7 pm. During fasts, participants are encouraged to drink zero-calorie beverages.

Pros:

• Great for weight loss: Forcing the body into a brief starvation period results in a reliance on fat for energy, burning through the body’s preexisting stores. Combined with exercise, doctors say that this is a perfectly healthy dietary strategy.
• Helps arthritis: The waves of ketosis result in waves of sudden waves of fat burning. This pattern of on-and-off ketosis can reduce triggers of arthritis flare-ups.
• May help various diseases: Though there is no clear-cut evidence as of yet, studies seem to suggest that periodic fasting can help with neurological disorders and cardiovascular disorders (like reducing your risk of heart disease).

Cons:

• Can be dangerous: Always consult a doctor before fasting. Fasting for too many consecutive days can trick your body into thinking you are actually starving, causing it to slow your metabolism and stop burning fat altogether.
• Controversial: Many survivors of eating disorders claim that this diet can trigger mental health problems, setting it up as the first building block in a long-term struggle with disordered eating. Whether dieting or not, food should never be viewed as an enemy!

The Mediterranean Diet 

This Mediterranean diet plan, created by the Harvard School of Public Health, actually started with a study of the Mediterranean region, where scientists noticed a pattern of higher life expectancies and lower rates of chronic diseases (along with less chance of high blood pressure, lower cholesterol, and other benefits). As the name might suggest, followers of this diet plan eat a diet of foods popular with those of that region.

This diet requires a slightly higher level of vegetables and healthy lean proteins (like chicken), but mostly fish. Healthy fats are encouraged as well, and olive oil is highly preferred to dairy-based fats like butter. This diet encourages participants to enjoy both frequent physical activity and the occasional glass of wine.

Pros:

• Not highly restrictive: Under this diet plan, participants are encouraged to enjoy many of the same foods they might usually, frequently just substituting unhealthy foods with fresher options.
• Reduces risk of cardiovascular disease: A study of over 25,000 women conducted over the course of twelve years showed that this diet reduced the risk of cardiovascular disease by ¼.
• Calming effect on the body: A diet heavy on healthy fats and fish has been proven to help with inflammation, making it a great choice for those suffering from arthritis.
• Promotes healthy aging: Nurses observed that strict followers of this diet seemed to age well, less frequently being bothered by neurological illnesses.

Cons:

• Not great for weight loss: This diet doesn’t especially emphasize low calories, particularly with its love for wine and olive oil.
• Few short-term effects: While this plan has been proven to stave off a variety of illnesses and disorders, these effects are only seen in those who follow this plan to its fullest extent for long-term periods of time.

A Plant-Based Diet 

Plant-based diets come in a variety of forms: a vegan diet is when you don’t consume animal products, vegetarians don’t eat meat, and flexitarians enjoy meat on occasion but primarily eat fruits and veggies.

While these options may result in different lifestyles day-to-day, they are surprisingly similar in execution. Regardless of the extent to which one chooses to follow a plant-based diet, theresults are largely the same, varying with the extremity to which someone omits animal products.

Pros:

• Great for weight loss: Followers of this diet are often forced to swap meat, which tends to be higher in fat and oil, for options that are naturally lower in fat and calories. Studies have proven that a side effect of this is weight loss.
• Improved cardiovascular health: Results from the Lifestyle Heart Trial showed that in a study of people suffering from heart-related illnesses, eighty-two percent saw a reduction in symptoms after switching to a plant-based diet.
• Lowers risk of diabetes: Yet another study showed that practicing a vegetarian diet lowers the risk of developing diabetes by half. For those already suffering, a plant-based diet resulted in a reduction or slowing of symptoms.
• Increased lifespan: Much like the Mediterranean diet, studies seem to suggest longer, healthier lifespans in those who practice a plant-based diet.

Cons:

• Protein shortage: The most common source of protein is meat, making it easy to fall behind in this important macronutrient when following a plant-based diet.
• Missing vitamins: There are some nutrients that are difficult to maintain without a regular serving of meat. It's easy to fall short on a variety of important vitamins when following this diet, meaning that practitioners are likely going to need the help of supplements.

Conclusion 

As is often the case with health-related topics, there is no perfect plan for everyone. What works perfectly for one person very well may be detrimental to another person’s health. What is most important is that everyone following a strict diet begins the process with a clear head and solid understanding of what that diet entails, both the pros and cons.

Sources:

Keto Diet | Family Doctor

Intermittent Fasting | Family Doctor

Diet Review: Mediterranean Diet | Harvard

Nutritional Update for Physicians: Plant-Based Diets | NCBI