Adopting a well-designed nutrition plan is a powerful tool that can simplify your life, improve your health, and make eating a pleasure. Despite these benefits, identifying the best individual approach can be daunting. The truth is that no single diet is best for everyone. Because we all have unique genes and preferences, what works for one person may not work for someone else.
This article reviews several popular nutrition plans and the science behind them. Although personalizing your chosen nutrition can yield better results, be aware that straying too much from the structure of a well-designed diet can be problematic.
Most diets are successful because they limit what you can eat, leading to reductions in calorie intake and insulin release. Deviating too much from the rules often negates the benefits and sets you up for another failed diet. With that in mind, it’s always safe to experiment with the following aspects of a particular plan:
With those principles in mind, let’s take a look at the pros, cons, and pitfalls of six of the most talked about nutrition plans.
#1: The Keto Diet
The most popular diet of 2019, the keto diet changes your metabolism by running the body on fat-derived ketones instead of glucose.
The Premise: By eating meals shunning carbs in favor of dietary fat, insulin decreases, allowing your body to enter a state of ketosis to burn fat instead of glucose. By using ketones for energy, you radically decrease hunger, have an easier time managing body weight, and reduce risk of diseases like diabetes, heart disease, and Alzheimer’s.
How It Works: Load up on healthy fat, avoid sugar and starch, and be sure to get your protein in. Favor whole foods and aim for variety, eating plenty of low-carb vegetables, meat, dairy, seafood, nuts, and seeds. Minimize fruit, starchy vegetables, and legumes while avoiding all processed carbs, grains, and added sugar.
Macronutrients: Aim for 70-80 percent fat, 15-25 percent protein, and less than 5 percent of calories from carbs (most people need to clock in below 50 grams of carbs a day).
Food Restriction: Higher carb foods, including all processed carbs, starchy vegetables, and fruit.
Sustainability: It depends. Keto is highly restrictive and requires diligence. For the fitness enthusiast who wants to lean up, keto may be best as a short-term intervention. For individuals battling chronic disease, such as diabetes or obesity, making the effort to adopt a low-carb keto lifestyle can offer tremendous benefits, allowing for the elimination symptoms and getting off medications for the long-term.
Best For: Short- and long-term fat loss. Diabetes and disease prevention. Managing brain disorders.
Impact on Hunger: Decreases hunger.
Impact on Muscle Mass: Maintains muscle especially when combined with a resistance training program.
Impact on Insulin: Decreases insulin.
Pros: A review of studies shows keto is better for long-term fat loss than low-fat, calorie restricted diets. Research also shows benefits for managing type 2 diabetes, treating epilepsy and other brain disorders, and fighting cancer. It may also enhance long-duration endurance performance and can be used by strength athletes to improve body composition without compromising performance.
Cons: The keto diet requires an initial run-in period while the body adapts to using ketones. Known as the “keto flu,” you may feel fatigue and low energy. These symptoms and others (constipation, “keto breath”) will go away once the body completes the adaptation period (usually 5 days to 2 weeks).
Keto requires planning, so it’s not appropriate for someone who has no time to devote to food prep or is chronically stressed. And there’s also the carbohydrate restriction, which can be a deal breaker for some. Although there is no biological requirement for carbs (as there is for protein and fat), our brains are evolutionarily hardwired to seek out carbs as a protective mechanism against starvation from our hunter-gatherer days when there was no grocery store at the end of the block.
Biggest Pitfall: Not sticking with the program through the adaptation phase. The process of shifting the body from running on glucose to using ketones takes time as the body upregulates the metabolic enzymes necessary for burning fat. By staying the course, you give your body the time to make the transition and reap the benefits of an optimized metabolism.
#2: Low-Fat, Calorie-Restricted
The low-fat diet has fallen out of favor as research shows the benefits of healthy fat and the pitfalls to chronic low-fat, higher carb dieting.
The Premise: Losing body fat requires a calorie deficit. Because dietary fat is more than double the calories of carbs or protein, reducing it will help create a calorie deficit, inducing weight loss.
How It Works: There are many iterations of the low-fat diet (popular versions include the DASH Diet, The Ornish Diet, and meal plans such as Jenny Craig). If fat loss is the goal, these diets recommend counting calories to ensure you create a calorie deficit.
Macronutrients: Varies, but generally 10-25 percent fat, 15-25 percent protein, and 60-70 percent carbs.
Food Restriction: Foods high in fat.
Sustainability: Unlikely. Although calorie counting can be a useful tool in weight management, it is synonymous with the “dieting mindset” in which you eat a certain way for a set period to lose weight. Once people stop counting calories and go back to less structured eating habits, they often regain any weight they had lost.
Best For: Short-term weight loss.
Impact on Hunger: Increases hunger.
Impact on Muscle Mass: Decreases muscle mass unless combined with a resistance training program.
Impact on Insulin: Decreases insulin.
Pros: Provides structure for people who like to feel they have control of their nutrition. Teaches portion control and can be most effective when combined with a recognition of the fact that food quality matters.
Cons: Unless it incorporates healthy eating and lifestyle habits, calorie counting is unlikely to be sustainable. Often associated with hunger and food deprivation, which can be unpleasant and difficult to maintain for the long-term.
Biggest Pitfall: Most low-fat, calorie restricted diets are short-term enterprises that don’t teach healthy eating habits, which sets dieters up for rebound fat gain and a lifetime of yo-yo dieting.
#3: Intermittent Fasting
One of the newer darlings of the nutrition world, intermittent fasting can be a useful tool for resetting metabolic function with scheduled fasts that increase fat burning and allow for the restoration of insulin sensitivity.
The Premise: By incorporating periods of fasting into a day or week, you can lower your calorie intake to lose body fat.
How It Works: There are many options but the most popular versions are Time Restricted Feeding (TRF) and Alternate Day Fasting (ADF). With TRF you eat a set number of meals over a set period each day (usually 1 to 3 meals over 8 to 12 hours). With ADF, you pick 2 or 3 non-consecutive days to fast, eating only one meal of about 500 calories, but you can eat normally the other days.
Macronutrients: Varies but best results will come from more balanced intake such as 20 to 30 percent protein, 30 to 40 percent fat, and 30 to 40 percent carbs. Most important is sufficient protein to maintain muscle mass despite extended periods without protein synthesis-stimulating amino acids.
Food Restriction: Time based restriction of all calorie containing foods.
Sustainability: Can be used long-term if you experiment and find the approach that best suits your needs.
Best For: People who don’t like chronic calorie counting but don’t mind limiting food intake sporadically. Useful for people who are busy if they ensure they are getting high-quality meals at set times.
Impact on Hunger: Depends. People often experience hunger pangs initially but find they go away with if they focus on something else.
Impact on Muscle Mass: Depends. Can maintain muscle if adequate protein is provided with best results in conjunction with a resistance training program.
Impact on Insulin: Decreases insulin.
Pros: Improves insulin sensitivity and allows the body a chance to tap into fat stores. Can be useful for fat loss and weight management while also improving metabolic function and other health markers such as cholesterol and triglycerides. Some individuals find it easier to limit food intake on certain days (or at certain times) rather than counting calories every day.
Cons: Alternate Day Fasting can be stressful or lead to food preoccupation. Research suggests that response to longer fasting windows varies with some people experiencing dysregulation of hunger hormones and increased stress whereas others have the opposite experience. People at risk of eating disorders or OCD should be cautious with fasting and opt for a structured TRF program with a longer eating window (12 hour).
Biggest Pitfall: Forcing yourself to perform long fasting bouts despite hunger or low energy may alter hormone balance or lead to preoccupation with foods, setting you up for disordered eating and other complications.
#4: Whole 30
One of the most popular diets in recent years, the Whole 30 is a short-term elimination diet that allows you to establish healthier eating habits while removing common “trigger” foods that stimulate inflammation or gut problems.
The Premise: By eating whole foods and eliminating sugar, processed foods, grains, diary, legumes, and artificial ingredients it is possible to “reset” the body and heal inflammation and damage to the gut. By “cleaning” up your eating for 30 days you will have more energy and feel better overall.
How It Works: For 30 days, design meals around meat, seafood, eggs, vegetables, fruit, and healthy fat. Eliminate dairy, grains, most legumes, sugar, and processed foods. Whole 30 is very strict and one slip up sends you back to day one. After the 30 days are finished, you can reintroduce those foods, paying attention to how they make you feel.
Macronutrients: Depends but is likely to be a relatively balanced macro breakdown in the range of 25 to 35 percent protein, 30 to 40 percent carbs, and 30 to 40 percent fat.
Food Restriction: Dairy, grains, legumes other than “pod” legumes such as green beans and snap peas, sugar of any kind (including honey, maple syrup, agave, stevia, and artificial sweeteners), processed foods (baked goods, junk food, sweets), and alcohol.
Sustainability: Unlikely. Whole 30 isn’t designed to be a long-term approach. The goal is to avoid foods associated with gut issues and inflammation and give you the time to mentally and physical kickstart healthy nutrition so that you can establish eating habits that nourish you.
Best For: Anyone who likes rules and wants to know exactly what they can and can’t eat. Useful for people experienced in healthy eating who want to start fresh with their nutrition.
Impact on Hunger: Depends. Often people experience an increase in cravings for off-limit foods initially, but hunger goes away after a week or so, especially if you eat sufficient protein, healthy fat, and vegetables.
Impact on Muscle Mass: Likely to maintain muscle as long as protein needs are met (1.2 to 1.6 g/kg of bodyweight a day) and resistance training is performed.
Impact on Insulin: Likely decreases insulin. No research has been done on Whole 30 but whole food diets that eliminate sugar and processed carbs consistently show reductions in insulin and blood sugar.
Pros: Eliminating sugar and processed foods in favor of whole food-based eating is always a smart approach, especially when emphasizing a variety of vegetables, seafood, meat, nuts, eggs, and fruit.
Cons: There’s no detailed plan after the 30 days, so if you don’t establish healthy eating habits, you’re unlikely to maintain fat loss or reap other benefits.
Although the off-limit foods can be problematic, there is no guarantee that eliminating them will be beneficial on an individual basis. For example, although some people are intolerant to dairy, dairy products perform extremely well in studies testing their impact on health markers and body composition. Legumes and whole grains (to a lesser extent) also perform well in studies, provide variety, and an array of nutrients.
Biggest Pitfall: Lack of a plan for once your 30 days are up. Time limited diets often lead people to endure eating in an unnatural way until “one day in the future” when they can return to their old eating habits. This approach sets you up for rebound weight gain and health issues since yo-yo dieting leads to more inflammation and worse cardiovascular health than if you hadn’t lost weight at all.
The popularity of plant-based eating has increased the spotlight on the vegan diet recently. Committed vegans generally have strong ethical beliefs that allow them to follow this restrictive diet easily.
The Premise: There are many motivations for a vegan diet but the main rule is to avoid all animal products in favor of plants. Motivations for going vegan include ethical, environmental, and health reasons.
How It Works: Eat only plants and avoid all animal products including meat, seafood, eggs, dairy, honey, gelatin, and supplements derived from animals.
Macronutrients: Varies, but generally higher carb in the 50 to 75 percent range, moderate fat (20 to 40 percent), and lower protein (10 to 20 percent).
Food Restriction: Meat, seafood, dairy, eggs, honey, gelatin, whey protein, and any animal derived supplements.
Sustainability: It can be sustainable, especially if you have a strong ethical commitment to a vegan lifestyle. Health-motivated vegans will likely get better results if they opt for whole foods and establish lifestyle habits that encourage success (cooking at home, eating a variety of foods, supplementing when needed, and exercising).
Best For: People with a strong ethical commitment to protecting animals and the planet.
Impact on Hunger: Depends. Hunger may increase during the initial transition to a vegan diet but it is likely to decrease over the longer term due to the substantial fiber provided on a well-designed vegan diet.
Impact on Muscle Mass: Likely to decrease unless you combine resistance training and adequate protein. Vegan protein needs will be higher (1.6 to 1.8 g/kg of body weight is recommended) than on an omnivorous diet).
Impact on Insulin: Depends. If you eat a whole-food vegan diet with relatively balanced macronutrients, blood sugar will be better regulated and insulin will go down. On the other hand, if you opt for a higher carb intake and eat more processed foods and sugar, insulin may increase.
Pros: A well designed vegan diet can be useful for weight loss and improving metabolic markers. Eating vegetables, fruit, beans, and non-gluten grains is never a bad idea. In comparison to the typical western diet, a vegan diet is likely to be more nutritious and will lower risk of heart disease and diabetes and may protect against cancer.
Cons: Vegan diets are deficient in certain nutrients that must be supplemented—vitamin B12, omega-3 fatty acids EPA and DHA, and vitamin D. Additionally, plant-based iron and zinc are poorly absorbed and vegans often suffer from anemia and other conditions if these deficiencies aren’t effectively addressed. Protein intake requirements increase on a vegan diet, especially for athletes because plant proteins are of lower quality and provide less of the protein stimulating amino acid leucine than animal proteins.
Biggest Pitfall: Not eating a well-rounded diet and setting yourself up for deficiencies, hormone and neurotransmitter imbalances, and health problems. By eating a wide range of vegetables, fruit, beans, and whole grains it is possible to hit most nutrient needs but you still need to prioritize protein at every meal and supplement strategically.
A well-designed Paleo diet is a kinder, gentler version of the ever popular keto diet.
The Premise: Our genes have adapted to eating particular kinds of foods. Eating the way our hunger-gatherer ancestors ate before industrial agriculture was developed will allow us to overcome modern diseases such as obesity, heart disease, diabetes, etc.
How It Works: Eat foods in their most natural state. Design meals around grass-fed meat, seafood, vegetables, fruit, eggs, seeds, and nuts. Some more flexible versions allow for dairy such as cheese and butter.
Macronutrients: Generally 30-40 percent fat, 20-30 percent protein, and 30-40 percent carbs, though it can vary.
Food Restriction: Processed foods. Sometimes dairy, grains, and other products of industrial agriculture.
Sustainability: It can be if you make the effort to develop lifestyle and nutrition habits that fit your preferences and needs.
Best For: Long-term fat loss, overcoming metabolic disorders, health and wellness.
Impact on Hunger: Neutral/Reduces
Impact on Muscle Mass: Maintains muscle when combined with a resistance training program.
Impact on Insulin: Decreases
Pros: If done correctly, Paleo is an easy to follow framework for healthy eating that can yield many benefits: Fat loss, improved body composition, maintenance of muscle mass, lower insulin, better cholesterol markers, and less risk of diabetes and other chronic diseases.
Cons: Paleo can be overly restrictive for some people, requiring the elimination of processed foods and added sugar. Mainstream nutritionists don’t like it because it removes whole grains and legumes, which they consider healthy, and allows for higher intake of animal products and saturated fat. Well-designed studies have shown saturated fat is benign and eating animal products in reasonable quantities while emphasizing an array of vegetables, fruit, nuts and seeds can provide all the necessary nutrients for a healthy diet. However, most people load up on animal products, while skimping on plants, leaving them at risk of missing out on essential nutrients and fiber. Another potential pitfall could be eating too much fruit if the goal is fat loss, though this is not a common problem.
Biggest Pitfall: Cutting carbs too low in favor of meat and fish. Many people view paleo as a low-carb diet, when in reality, hunter-gatherers get an average of 35 to 40 percent of calories from whole carbs, including fruits and vegetables, especially higher calorie tubers. The key is to remove added sugar and simple carbs, filling your plate with fiber-rich vegetables and fruit.