Pros and Cons of Popular Diets | Episode 9

The carnivore diet. The keto diet. Intermittent fasting. Plant based. The [insert diet here]… There are so many popular diets out there being promoted by various diet tribes, many of which have limited evidence for their efficacy. All of which have various positives and negatives associated with them. In this episode, I systematically break down some of the most popular diets and discuss both the positives and negatives to these dietary approaches. If you are confused by all the noise on social media, this episodes is a MUST LISTEN to help simplify things for you!

Flexible Dieting

Flexible diet control has been shown to reduce the risk of disordered eating compared to rigid diet control. Rigid dieting is also associated with great BMI/body fat levels. 1 2

Flexible dieting produces similar weight loss to rigid dieting despite allowing for more food choices when calories are equated. 3 4

Flexible diet control may also be superior in a free living setting where people are not told how many calories to consume. 5

Contrary to popular belief, those following flexible dieting principles tend to consume a more diverse array of micronutrients than those following rigid diets. 6

Flexible dieting can work in conjunction with virtually any other diet, it is not mutually exclusive with any other dietary approach.

Flexible dieting requires cognitive restraint that includes either calorie tracking, macronutrient tracking, portion control, or exchange systems. Some form of diet monitoring must be practiced, whereas other rigid diets may not place restrictions on amounts of foods due to decreased palatability of rigid diets. You can eat whatever you want, you just can’t eat however much of it you want

Some people may take flexibility to the extreme & use ‘flexible dieting’ as an excuse to incorporate as much junk food as possible into their diet

Mediterranean Diet

Mediterranean Diet (MD) is a diet that focuses on the a style of eating similar traditional food patterns of countries bordering the Mediterranean Sea, emphasizing plant based foods, lean meats, and health fats: Specifically focusing on Fruits, vegetables, whole grains, legumes, nuts, fish, poultry, eggs, and low-fat dairy. Red meat is allowed but recommended to be limited. Olive oil is recommended as a healthy fat
This diet is consistently a top performer for reducing cardiovascular disease risk. Compared to other forms of dietary care, the MD diet reduced risk of CVD by 10-65% and risk of CVD mortality by 40-53%. 7 8 9
Adherence to the MD is better than the dietary approach to stop hypertension (DASH) diet which is also an effective treatment for CVD. 10
The protective effects of MD on CVD appear to mostly be attributable to increased consumption of fruits, vegetables, legumes, and olive oil. 11
The MD appears to also reduce the risk of cancer and cancer mortality. 12 13
The MD diet reduces the risk of all cause mortality. 14 15
May not be suitable for those who are vegetarian or vegan as it promotes the consumption of some animal products. Likely suitable for pescatarians
Limits consumption of many foods and may be difficult to adhere to for some individuals who have an aversion to these recommended foods
Adherence to the MD is associated with higher monetary cost of diet. 16

Plant Based Diets (PBDs) – Vegan, vegetarian, and pescatarian diets

PBDs are some of the top performers when it comes to reducing CVD risk and CVD mortality. 17 18

PBDs also appear to reduce the risk of cancer incidence. 19

A healthy plant based diet may reduce the risk of mortality. 20 21

PBDs strictly limit or completely eliminate animal products, making them difficult for some people to follow.

PBDs may increase the risk of hemorrhagic stroke (but decreases risk of ischemic stroke) but the effect is inconsistent in research studies. 22

PBDs are at risk for lower iron and vitamin B12 levels. 23 24

While healthy plant based diets may reduce cancer and CVD risk, there are a myriad of ultra-processed calorie dense ‘plant based’ foods on the market and an unhealthy plant based diet may increase cancer, CVD, and mortality risk. 25 26 27

Low Carb Diets (LCDs): Ketogenic, Atkins, and low carb

NOTE: broadly this category in research literature is typically defined as less than 40% of total calories from carbohydrates. Some may not consider this low carb but that is typically the cut off in the literature. A traditional ketogenic diet is typically over 70% of calories from dietary fat, whereas a more modern ketogenic diet like Atkins is closer to 50-60% of calories from dietary fat and proportionately more protein than a traditional ketogenic diet which is ~10-15% of calories from protein

LCDs produce more weight loss in the short term (<12 months) than low fat or balanced diets in free living settings where subjects are not confined to equal calories. 28 29 30
LCDs do not produce superior weight loss, fat loss, body composition when calories are equated between diets. They also do not appear to produce better overall improvements in blood lipids, or glycemic control compared to calorie equated low fat or balanced diets (though some specific markers may improve slightly more). 31 32 33 34 35 36
LCDs may reduce triacylglycerides, fasting insulin, and increase HDL more so than low fat or balanced diets even with calories equated between diets in the short term. 37 38
Low carb diets can increase LDL Cholesterol (LDL-C) and ApoB, which are independent risk factors for CVD. 39 40 41
LCDs may not require calorie tracking or macronutrient tracking as LCDs tend to improve satiety compared to mixed diets or low fat diets. 42 43
LCDs are associated with increased incidence of disordered eating. 44
LCDs may increase the risk of CVD and mortality possibly mediated by the focus on foods high in saturated fat. 45 46

Carnivore Diet (CD)

Popular diet with an enthusiastic following, but limited evidence for efficacy
Very simple to follow as you only consume animal products, mostly meat
Very easy way to consume high quality animal protein
Diet may improve satiety based on anecdotal evidence
CD may reduce TAGs & increase HDL based on self reported survey data. 47
Diet is utterly devoid of fiber, this may lead to increased risk of CVD, cancer, and mortality. 48 49 50
Low fiber diets may also increase risk of colorectal cancer specifically and other GI disorders. 51 52 53 54
CD may lead to greater rates of weight regain. 55

Time Restricted Feeding (TRF)

More commonly referred to as intermittent fasting (IF) and includes alternate day fasting (ADF), 5:2 diet, 16:8 IF, 18:6 IF, 20:4 IF, etc and one meal a day (OMAD)

Simple diet to follow as it is confined to specific feeding windows or days.
Not mutually exclusive with any other diet, although it is commonly associated with LCDs.
Some people find it very easy to adhere to
Appears to spontaneously cause people to reduce their calorie intake in free living situations. 56
Results in similar improvements in body weight, insulin sensitivity, and blood lipids compared to non-TRF diets when calories are equated between diets. 57 58
TRE may decrease lean body mass (LBM) relative to isocaloric non-TRF diets. 59 60 61 62
TRE is associated with increased incidence of disordered eating. 63 64

References

Intro
Bodybuilding History
Flexible Dieting
Carbon Diet Coach
Mediterranean Diet
Plant Based Diet
Low Carb Diets
Team Biolayne
Carnivore Diet
Fasting Diets
Summary

Mentioned in this episode