Intermittent Fasting
Intermittent fasting describes a pattern of eating, incorporating periods of low to no caloric intake, but not necessarily what to eat. The ideas and interpretations vary, from limiting your food intake to certain hours of the day (e.g. 8am-6pm), to certain days of the week (e.g. fasting on Saturdays), to certain longer periods of time (e.g. fasting for consecutive days during the year). One of the theories behind intermittent fasting has to do with our insulin response. When we eat, food gets broken down into building blocks. Carbohydrates are broken down into glucose, which, when it enters the bloodstream, then triggers insulin to be released. Insulin is responsible for getting that glucose out of the bloodstream and into brain and muscle cells (for energy), liver cells (for storage as glycogen) and fat cells (for storage as fat). Too much insulin can cause cells to be less responsive to it, leaving glucose in the bloodstream to wreak havoc, a condition called insulin resistance. When we don’t eat, we don’t release insulin and therefore, we don’t put as much into storage and instead, force our bodies to take energy out of storage, thereby causing weight loss and reversing insulin resistance. Intermittent fasting can often be done in conjunction with a specific eating plan, like the Paleolithic diet or “Paleo.”
Why try it?
The main reason people try this eating pattern is to lose weight. Fasting can affect different hormone levels in the body (besides insulin) that lead to weight loss. Fasting and cutting down on snacking in general can improve insulin resistance as reviewed above. A 2017 review in the Annual Review of Nutrition cited limited data suggesting that intermittent fasting can offer protection from heart disease and cancer as well as some neurodegenerative diseases (like dementia).
Think twice:
This is not a silver bullet. More robust studies are necessary to confirm that those benefits are real and significant. Fasting is a physical stress on the body and can trigger cortisol response which may cause fluctuating energy levels and interrupt sleep. It can result in low blood sugar, fatigue and delayed cognition (brain fog). Fasting may not be safe in pregnancy or in patients with certain health conditions like diabetes.
Learn more about intermittent fasting with us!
Paleolithic Diet or “Paleo”
The Paleo diet consists of eating foods that can be hunted and gathered, like our “caveman” ancestors. This means cutting out things like grains, dairy, legumes, processed foods, processed sugar. This generally results in a diet that is high in lean protein, high in fiber and low in carbs. One hypothesis behind this choice in nutrients is that our bodies are not genetically equipped to process a diet created by farming practices because this change happened more quickly than our bodies were able to adapt.
Why try it?
Paleo is considered a healthy diet as it generally contains lot of veggies, fruit and nuts. By cutting out processed and high sugar foods, weight loss is inevitable, other health benefits of Paleo may include improved insulin resistance, blood pressure and cholesterol cholesterol parameters (as suggested by this review in the American Journal of Clinical Nutrition).
Think twice:
Whole grains, legumes and dairy can also be part of a healthy diet and contain other vitamins and nutrients (and in the case of dairy, calcium) that are important for good cellular growth and function. Getting grass-fed meat/wild game can be cost-prohibitive for some. And, as in intermittent fasting, there are no long term studies to prove the health benefits are significant and outweigh potential risks. In fact, the Australian Family Physician published a good summary of study results on the Paleo diet and there just isn’t enough good data. Besides, do we actually know if cavemen were healthier because of this diet?
Low-carb
A low-carb diet limits the amount of carbohydrates you consume and instead promotes higher protein and fat intake. The idea is based on the fundamental fact that your body prefers glucose as its energy source. When you consume carbs, they get broken down to glucose, so your body is happy. Any extra glucose gets stored as fat. But, if you cut down on carb intake and eat fat, you are forcing your body to breakdown fat to create ketone bodies, which your body uses as a substitute for the glucose. This state is called ketosis. There are many variations of this diet based on the amount of carbs that are recommended. The quintessential low-carb diet is the Atkins diet, which allows 5-15% of carbs. In recent years, the Ketogenic, or Keto, diet has made a comeback and this diet allows from <5% to 10%. The focus with the Keto diet is heavily leaning toward fat. The South Beach diet can be considered a modified low carb diet–though it does not restrict carb intake, it shifts the focus to healthier (lower glycemic index) carbs, lean protein and healthy fats. It also promotes eating 6-7 times per day.
Why try it?
Again, many people choose this type of diet to lose weight. Weight loss is achievable on this diet. Low-carb diets may also improve your blood sugar and insulin response. As of yet, there is no evidence to show there are any heart health benefits from following a low-carb diet.
Think twice:
Low-carb diets, especially severe/strict low-carb diets can result in vitamin or mineral deficiencies since they limit nutrients found in whole grains, fruits and vegetables. Ketosis can have side effects as well, including gastrointestinal disturbances, nausea, bad breath, headache, mental and physical fatigue, kidney stones, and dehydration. The classic ketogenic diet was initially developed as an intentionally extreme diet (used to treat seizures in children) and required physician supervision in the hospital during initiation because of the risk of complications. Intentionally putting yourself in ketosis may not be safe during pregnancy and while breastfeeding.
Mediterranean
Inspired by eating habits of the Greeks, Southern Italians and Spaniards, this diet encourages intake of plant based foods (fruits/veggies, whole grains, legumes, nuts), choosing fish and poultry in moderation, limiting red meat, replacing butter with healthy fats like olive oil. It does allow for red wine in moderation and also encourages regular exercise as part of the plan. The specific diet may look slightly different from region to region, but follows those general guidelines.
Why try it?
The Mediterranean diet is one of the most well studied diets over the past decade. Consistent data point to the heart health benefits of the Mediterranean diet. Meta-analyses (read: statistical gymnastics on data from multiple studies) such as this one from the journal Nutrients have also shown an association between following the Mediterranean diet with lower risk of coronary artery disease, diabetes, cancer and dementia.
Think twice:
The Mediterranean diet can be difficult for people who have food intolerances, like gluten or dairy, though substitutions can be made easily. In general, there are not many drawbacks to this well-rounded lifestyle plan.
Vegetarian/Vegan
Vegetarianism is a diet that excludes all meat, but may (or may not) animal products such as milk/dairy, eggs, honey. There are many variations on being vegetarian, such as lacto-vegetarianism (vegetarian diet but includes dairy), pescatarianism (vegetarian diet but includes fish). Veganism is also a type of vegetarian diet which excludes all meat and animal related products.
Why try it?
People choose a vegetarian diet for a variety of reasons, from animal welfare to religion to sustainability and carbon footprint. Diets that emphasize consumption of veggies, fruits, legumes, whole grains, seeds and nuts are naturally low in saturated fats and higher in fiber and vitamins and minerals. Some studies, such as this suggest longevity, heart health, lower risk for diabetes as benefits of a vegetarian diet, but I did not find many randomized controlled trials (the gold standard) evaluating these benefits.
Think twice:
A healthy vegetarian diet takes planning. Vegetarian sources of iron, calcium, zinc and in particular are not as well absorbed as meat sources of those same nutrients. B12 is only found naturally in animal products, but can be fortified in some vegetarian products. Vegans in particular need ensure adequate calcium, Vitamin D and omega-3 intake. It is also particularly easy to consume higher amounts of processed foods (calling yourself a vegan with a diet of orange soda, potato chips and veggie burgers isn’t necessarily healthier). If you try vegetarianism is important not to simply avoid meat, but to diversify the plant protein sources in your diet by doing things like eating more beans and lentils.
Weight loss plan such as Weight Watchers
Weight Watchers is a popular weight loss program, having survived many diet trends, and has created a name for itself around the world (30 countries?!). Weight watchers encourages healthy eating and regular exercise to lose weight by creating a calorie deficit. The program has simplified nutrition label reading using a system of “SmartPoints,” which assigns points to a food based on calories, saturated fat, sugar, and protein.
Why try it?
The program does not restrict any particular food and can be easily adapted to any food preferences or diet. Weight Watchers has online tools, coaches and brick-and-mortar studios to allow for more accountability, guidance and flexibility. A systematic review in 2015 showed that participants lost 2.6% more weight than the control group at 1 year. Over the long term, new habits are created and can lead to successful weight loss and maintenance of goal weight.
Think twice:
This program is focused on weight loss and may only be accessible to people who can afford the $45/month. It also doesn’t distinguish between good and bad calories, so theoretically, you can allocate all of your points to “treats” and eat lots of zero point foods to balance.
DASH Diet
The DASH Diet was initially developed by the National Heart, Lung and Blood Institute as Dietary Approaches to Stop Hypertension, but is now being promoted to help with weight loss. It encourages intake of fruits, veggies, low fat/nonfat dairy, whole grains, lean meats/fish/poultry, nuts and beans. Sweets, sugar-sweetened beverages, and foods high in saturated fats are limited on this diet. To lower blood pressure, the sodium limit is at 2300mg/day or for even more lowering, 1500mg/day, encourage intake of potassium, magnesium and calcium instead.
Why try it?
Multiple NHLBI studies (DASH trial, OmniHeart and Premier) have demonstrated lower blood pressure and LDL cholesterol in patients who follow this diet. The DASH diet website suggests it is the American version of the Mediterranean diet. This diet does not restrict any food categories and encourages high intake of fiber and heart healthy fats. Per the 2010 Dietary Guidelines by the USDA, The DASH diet was promoted as a type of diet that followed the Guidelines. Aside from the blood pressure lowering benefits, you may find weight loss, improved heart health, and lowered risk of diabetes and stroke as additional effects of following this plan.
Think twice:
Low-fat/nonfat dairy can also mean added sugar and lower protein levels for some, this isn’t better. However, as it is relatively well balanced and can be modified for a variety of tastes and food restrictions, many people could adapt this as part of a sustainable lifestyle plan.
Dr Lisa Nguyen
Other useful resources:
Current USDA Dietary Guidelines
Harvard TH Chan School of Public Health – The Nutrition Source
