Table of Contents:
Intermittent fasting
Low-carb diet
Ketogenic diet
Palaeolithic diet
Low-fat diet
Mediterranean diet
Dash diet
How Forward can help you lose weight—permanently

“Miracle” weight-loss diets have been all the rage since the mid-1800s, when William Banting published the first-ever diet book, “Letter on Corpulence.” Since then, we’ve seen the rise and fall of a long list of fad diets: the Grapefruit Diet , the Lemonade Diet, the Last Chance Diet, the Green Juice Diet, the Chewing Diet, the Peanut Butter Diet, the Shangri-La Diet, the Cabbage Soup Diet, and too many others to name.

Fad diets don’t lead to long-term weight loss. They never have, and they never will. They have one thing in common: they don’t follow science—at all. While some fad diets will melt off pounds for the short-term, eventually, you will hit the dreaded weight-loss plateau—if you can stay on the diet for that long. Because another thing fad diets have in common is that they’re just not sustainable. 

So today, we’re going to talk about weight-loss diets—but not of the fad variety. Rather, these are popular ways of eating that have been shown through research to help people lose weight. But how well do they work—are they sustainable? Are they healthy? Let’s find out.

Intermittent fasting

Intermittent fasting is an eating pattern that involves alternating between periods of eating and periods of not eating (fasting.) It’s commonly used as a method of weight control and weight loss. The three most popular methods of intermittent fasting are:

  • The 16/8 method restricts eating to an 8 hour period of the day and fasting for the other 16 hours.
  • The Eat-Stop-Eat method involves not eating anything for one or two 24-hour periods throughout the week.
  • The 5:2 method involves restricting yourself to a very low caloric intake twice a week, usually 500-600 calories for two non-consecutive days.

How does intermittent fasting work?

Intermittent fasting impacts hormone levels in a way that promotes weight loss. It increases the body’s production of norepinephrine, a hormone that burns fat. Intermittent fasting doesn’t reduce weight any more quickly than other calorie-restrictive eating regimens, but it’s associated with less muscle loss while you’re losing weight. Intermittent fasting also reduces insulin resistance—but it doesn’t reduce blood glucose levels.

Pros and cons of intermittent fasting

Intermittent fasting is safe for most people. Nearly all studies on intermittent fasting have found some degree of weight loss—from 2.5 to 9.9 percent of body weight—and fat loss with this way of eating.


  • Increased metabolism
  • Substantially decreased belly fat, which can build up around internal organs and cause disease.
  • Less muscle loss than a standard calorie restriction diet.
  • Reduced blood pressure.
  • Improved insulin sensitivity.


  • Hunger and cravings may be more intense for the first few days after beginning intermittent fasting.
  • Lightheadedness and headaches are common side-effects of intermittent fasting. 
  • You may experience constipation, bloating, nausea, or diarrhea during intermittent fasting.

Low-carb diet

A low-carb diet is an eating strategy that can help you lose weight by reducing the number of carbohydrates consumed in a day. The typical American consumes 44 to 65 percent of their calories from carbohydrates, which primarily come from grains and fruit. A carb intake of less than 26 percent of total calories is considered low-carbohydrate. 

How does a low-carb diet help with weight loss?

One hypothesis is that lower carb intake results in lower insulin levels, which reduces the amount of carbs stored as fat in the body. Another suggests that since more fats and proteins are consumed in a low-carb diet, you’re not as hungry, so you eat fewer calories overall. Evidence also suggests that a low-carb diet increases metabolism

Because they result in rapid weight loss for 6 to 12 months, low-carb regimens are ideal for people who have obesity or type 2 diabetes. They may also help reduce triglyceride levels, which can help improve heart health.

Pros and cons of a low-carb diet


  • Rapid weight loss
  • Reduced triglyceride levels
  • Reduced need for insulin, which is beneficial for those with type 2 diabetics


There are hypothetical safety concerns surrounding low-carb diets. However, there is insufficient data to support these suppositions.

Keto diet

The ketogenic, or keto, diet is an eating program that dramatically reduces the intake of carbohydrates to 10 percent of your daily calorie intake while increasing dietary fat consumption.

How does it work?

The significant decrease in carbs and increase in fat associated with the keto diet puts the body into a state of nutritional “ketosis,” in which the body doesn’t have sufficient glucose to burn for energy, so it burns fat instead. In turn, the body produces ketones, which it uses as an alternative fuel to sugar. The increased burning of fat leads to weight loss.

The keto diet produces significant long-term weight loss and is ideal for patients suffering from obesity from metabolic syndrome. The keto diet also improves clinical markers for type 2 diabetes by significantly reducing sugar intake and improving the body’s response to insulin. However, people who have diabetes may experience dangerously low blood sugar levels and should talk to their doctor before starting a keto diet.

The keto diet results in significantly greater and more rapid weight loss than low-fat diets, as it helps to metabolize fat quickly rather than reduce the intake of fat. The keto diet isn’t meant to be a long-term eating plan and should be discontinued after 12 months under close supervision by your physician to monitor kidney function.

Pros and cons of the keto diet for weight loss


  • Rapid and sustainable weight loss
  • Increased metabolism
  • Reduced seizures in patients with epilepsy


  • It may be difficult to sustain a very low-carb diet.
  • Side effects may include fatigue, lIghtheadedness, headaches, nausea, and bad breath.

Paleo diet

The paleolithic (paleo) diet is a meal program centered around the idea that the hunter-gatherers of prehistoric times were healthier and suffered from none of the health issues we experience today. The paleo diet consists of only whole, unprocessed foods, and it’s considered a very low-carb diet.

How does the paleo diet work?

The paleo diet removes processed foods from the menu and replaces them with whole, natural foods. By eliminating processed foods and providing the body with filling, nutrient-rich foods, the body doesn’t have to work so hard to break down carbohydrates for fuel and instead metabolizes fats and protein, reducing the body’s weight from fat.

As with other low-carbohydrate diets, the paleo diet provides rapid and sustained weight loss and is a viable tool for managing your weight. 

Research suggests that consuming whole, unprocessed foods is far better for the body than eating the over-processed commercial foods that are available today. Removing highly-processed foods from your diet improves overall mortality and reduces the risk for a number of diseases, including heart disease and diabetes. 

Pros and cons of the paleo diet for losing weight



  • People using the paleo diet may experience deficiencies in calcium and vitamin D, so supplementation may be necessary.
  • People on the paleo diet need to monitor their saturated fat and protein intake, since overconsumption of these can increase the risk for kidney and heart disease and certain cancers. 
  • The paleo diet is very restrictive and difficult for many people to sustain.

Low-fat diet

A low-fat diet is an eating program that eliminates much of the fat — especially saturated fats — in your diet. The idea is that the less fat you eat, the fewer calories you consume, which helps bring about weight loss. 

How does a low-fat diet help you lose weight?

Fat is the macronutrient highest in calories, containing 9 calories per gram, compared to protein and carbohydrates, which each contain 4 calories per gram. So, reducing fat intake reduces calorie consumption, and should bring about weight loss. 

But different studies suggest different possible outcomes and often contradict other research into low-fat diets. Most older studies and meta-analyses that promote low-fat diets for health and weight loss draw on data that was provided decades ago. In more recent studies, though, some findings remain consistent:

  • Low-fat diets don’t produce the sustained weight loss often found with low-carb and Mediterranean diets. 
  • Low-fat diets don’t provide the same health benefits as low-carb and Mediterranean diets—especially if you have type 2 diabetes.
  • Unlike a low-carb diet, a low-fat diet by and large doesn’t reduce sugar or highly processed foods associated with a range of diseases, including diabetes, heart disease, and cancer.

Pros and cons of a low-fat diet


  • A low-fat diet can help you lose weight.
  • Eating less saturated fat helps reduce your risk of heart disease and certain cancers.


  • While a low-fat diet may help reduce “bad” LDL cholesterol, it’s also linked to decreased “good” HDL cholesterol levels. 
  • Low-fat foods often compensate for a lack of flavor with added sugars and other highly-processed ingredients that are counterproductive to your weight-loss goals.

Mediterranean diet

The Mediterranean diet is an eating program centered on the common eating practices of people in the Mediterranean region, who are known to suffer from less obesity and heart disease. This diet focuses on consuming more fruits and vegetables, whole grains, nuts, seeds, and heart-healthy olive oil—and less red meat, eggs, sugar, and dairy products. 

How does the Mediterranean diet work?

The Mediterranean diet is naturally low in carbohydrates and is touted as a heart-healthy diet due to its lack of processed foods, simple carbs, and added sugars. While it does promote weight loss and helps you maintain a healthy weight, the primary intention of the diet is to promote cardiovascular health.

A number of studies have shown a range of health benefits of a Mediterranean diet over a low-fat diet, such as reduced risk of heart disease, stroke, and type 2 diabetes as well as a substantial reversal of metabolic syndrome. 

Pros and cons of the Mediterranean diet


  • Weight loss.
  • Improved glycemic control and insulin resistance. 
  • Reduced risk of diabetes, heart disease, heart attack, and stroke.
  • A potential reversal of metabolic syndrome when healthy nuts are included.


Although a Mediterranean diet may reduce iron and calcium levels due to a lack of dairy products and red meat, supplements or certain other calcium- and iron-rich foods, like spinach, can help prevent deficiencies. 

The DASH diet

DASH stands for Dietary Approaches to Stopping Hypertension. This eating program is aimed at lowering high blood pressure and reducing associated health risks. The DASH diet is based on research showing that people who followed a plant-based diet had substantially lower instances of high blood pressure.

How does it work?

The DASH diet program focuses on plant-based foods, along with lean proteins like fish and poultry. It reduces fat intake and increases whole grain, fruit, and vegetable consumption. 

Although the DASH diet is engineered for people who have high blood pressure or who are at risk for developing it, this eating program can help you lose weight for the long-term. 

Pros and cons


  • Weight loss.
  • Reduced risk of heart disease, metabolic syndrome, diabetes, and some cancers.


  •  Research shows no down-sides to the DASH diet.

How to lose weight without “dieting”

The science of weight loss is complicated, but losing weight really doesn’t have to be. While a prescribed diet like any of the ones we listed above can help guide you to sustainable weight loss, many people have a difficult time adhering to strict rules around eating. So if the thought of adhering to a special diet fills you with dread, you’re not alone—and the good news is, you can lose weight without subscribing to a certain eating pattern, philosophy, or diet. 

As long as you strive to eat whole foods that are unprocessed and without added sugar in moderation, —you’ll lose weight. And if you do it for the long-term, your weight loss will be sustainable. 

If you find that your biggest barrier to weight loss is staying on track with eating healthy food and exercising regularly, learn how to get—and stay—motivated.

How Forward can help you lose weight for good

Our 12-week, doctor-led Weight Management Program can help you lose weight for better health and disease prevention. Our comprehensive program includes tests and assessments, education, support and monitoring, and a personalized diet and exercise program based on your goals, lifestyle, culture, and health goals. As your primary care provider, Forward is focused on your overall health and wellbeing—and that includes helping you reach your target weight—and maintain it for the long-term.

No long waits. One flat fee. No copays — ever.

Fed up with a soul-sucking healthcare system? Same. With unlimited visits, personalized insights and real, actionable results, find out what it’s like to actually enjoy seeing your doctor.