Harvard Review of 39 Diets Science vs. Non-Science
70/30 Food Sci & Tech
We make plant and fungi based functional ready meals for busy city people.
Author: 7030 Co-Founder, Jessica Woodruff, MPH, MS, CHES, CISSN
"The history of dieting shows vanity outweighs common sense."
——Melissa Wdowik
Assistant Professor of Food Science and Human Nutrition， Colorado State University
Diets, diets everywhere. Most are created with good intentions but gradually drift away from the original purpose – publishers and media want to capitalize on the trend and exploit the vulnerabilities and insecurities of people's intense, sometimes irrational, need to 'look healthy'.
How to decide which one is right for you? We give you this 7030 Guide to help you navigate the complex and fascinating world of nutrition science. We hope you achieve your wellness goals with this guide.
Remember, before starting?any?new diet, it is necessary to know a baseline for health. Before you try?any?diet, know where your bloodwork and overall physical health stand. Sometimes, symptoms do not show until the later stage of the disease, so prevention is always better than cure. This means at least a yearly check-up with a doctor. Example: Women aged 45 to 54 should get mammograms every year. In this article, we give you?Part 1 –?Harvard’s?Review of 39 Popular Diets + 7030 Cofounder Jessica's review of the Harvard Review.
7030 Co-Founder, Master in Public Health & Nutrition Science, Nutrition Science Researcher, Certified Practicing Nutrition Consultant
Let's look at what?Harvard's?new report has to say about diets. About the Harvard Review. The following is from their website:
"The Diet Review: 39 popular nutrition and weight-loss plans and the science behind them — the all-new report from Harvard Health Publishing, with the facts on more than three dozen different eating plans. Our experts reviewed each diet's claims and then looked at whether there was solid research to back them up."
PART A Harvard?Rating System
The report rated the diets based on Nutrition Science & Research-based evidence. They rank the strength of evidence available: Strong, Moderate, Weak, and Non-Existent.
What's the strength of the evidence for this diet? Is there specific research on the diet? If so, what type and how much? Is it direct evidence testing the diet itself to see if it produces either weight loss or a particular health benefit? Or is it indirect evidence showing that similar diets are helpful? —quote from?the Harvard?report
Harvard categorized these diets under Low Carb, Plant Forward (example: vegan), Intermittent Fasting (calorie restrictions), Disease Fighting, Traditional, Paleo (referring to cavemen, the stone age, etc.), and Weight Loss.
This article will highlight the strength of evidence for each diet.
Disclaimer: The diets are not ranked. Arranged in random order.
Diet#39
Carnivore Diet - Low Carb
A restrictive diet only includes meat, fish, and other animal foods like eggs and certain dairy products.
Harvard says the Strength of Evidence is: Non-Existent.
Diet#38
Dukan Diet - Low Carb
This diet is based on eating lean meat, poultry, fish, shellfish, fat-free dairy, and eggs.
Harvard says the Strength of Evidence is: Non-Existent.
Diet#37
Raw Food Diet - Plant Forward Diet
Allows food that is not heated over 104–118°F (40–48°C). It should not be refined, pasteurized, treated with pesticides, or processed.
Harvard says the Strength of Evidence is: Non-Existent + one negative study.
Diet#36
No-Diet – Weight Loss Diet
It recommends eating based on calorie density and categorizes foods as green, yellow, or red.
Harvard says the Strength of Evidence is: Weak.
Diet#35
South Beach Diet - Weight Loss Diet
It emphasizes eating food with a low glycemic index and categorizes carbohydrates and fats as "good" or "bad."
Harvard says the Strength of Evidence is: Weak.
Diet#34
Most significant Loser Diet - Weight Loss Diet
Named after the American TV reality show of the same name, it promotes weight loss by restricting calories and encouraging a diet comprising nutrient-dense, whole foods.
Harvard says the Strength of Evidence is: Weak.
Diet#33
Okinawan Diet – Traditional Diet
The Okinawa region's diet emphasizes vegetables and soy products alongside occasional — and small — amounts of noodles, rice, pork, and fish.
Harvard says the Strength of Evidence is: Weak.
Diet#32
Clean Eating – No category
Clean eating?focuses on consuming whole foods that are minimally processed and as close to their natural form as possible and avoids all oils and preservatives.
Harvard says the Strength of Evidence is: Weak.
Diet#31
5:2 Diet - Intermittent Fasting
The 5:2 diet involves eating what you typically eat every five days of the week and restricting your calorie intake to 500–600 for 2 days of the week.
Harvard says the Strength of Evidence is: Weak.
Diet#30
Alternate Day Fasting - Intermittent Fasting
On this diet, you fast every other day but eat whatever you want on the non-fasting days. On fasting days, you can drink as many calorie-free beverages as you like.
Harvard says the Strength of Evidence is: Weak.
Diet#29
Modified Alternate Day Fasting - Intermittent Fasting
On this diet, you fast every other day but eat whatever you want on the non-fasting days. On fasting days, you can eat up to 25% of what you eat on non-fasting days or up to 500 calories.
Harvard says the Strength of Evidence is: Weak
Diet#28
Macrobiotic Diet - Plant Forward Diet
Based on ideas about types of food drawn from Zen Buddhism, popularized by George Ohsawa. Supports eating whole and unprocessed foods. Allows animals products once a month, limits intake of tropical vegetables &fruits and ice-cold drinks.
Harvard says the Strength of Evidence is: Weak
Diet#27
Engine 2 Diet - Plant Forward Diet
A low-fat vegan diet that focuses on plant-based ingredients like fruits, vegetables, whole grains, and legumes avoids oil and allows 8% of calories from protein.
Harvard says the Strength of Evidence is: Weak
Diet#26
Whole 30 Diet - Paleo Type
It encourages followers to cut alcohol, sugar, grains, legumes, dairy, and additives from their diet for 30 days.
Harvard says the Strength of Evidence is: Weak
Diet#25
Pegan - Paleo Type
Hybrid of the Paleo and Vegan Diet. Mostly Whole Foods, less processed foods. 'If God made it eat it. If man made it, leave it.' Claims most wheat is genetically modified.
Harvard says the Strength of Evidence is: Weak
Diet#24
Mediterranean Paleo Diet - Paleo Type
Hybrid of the Mediterranean and Paleo Diet. This diet replaces meat with seafood and olive oil for fat, no lard. Avoid grains, legumes, and dairy.
Harvard says the Strength of Evidence is: Weak
Diet#23
Paleo Diet - Paleo Type
Includes?lean meats, fish, fruits, vegetables, nuts, and seeds; avoids grains, legumes, dairy, and processed foods.
Harvard says the Strength of Evidence is: Weak
Diet#22
Optavia Diet - Low Carb
Medifast, a meal replacement company, owns them. It is a?weight loss or maintenance plan?that prescribes eating a mix of purchased, processed food — called "feelings" — and homemade "lean and green" meals.
Harvard?says?the?Strength of Evidence is: Weak
Diet#21
Ketogenic Diet - Low Carb
In medicine, it is used mainly to treat hard-to-control (refractory) epilepsy in children. The ketogenic diet is a very low-carb, high-fat diet. It involves drastically reducing carbohydrate intake and replacing it with fat. This reduction in carbs puts your body into a metabolic state called ketosis.
Harvard?says the Strength of Evidence is: Weak
Diet#20
Eco Atkins - Low-Carb Diet
Eco-Atkins calls for 31% of daily calories from plant proteins, 43% from plant fats, and?26% from carbs.
Harvard says?the?Strength of Evidence is: Weak
Diet#19
Weight Watchers Diet - Weight Loss Diet
Weight Watchers, or WW is a commercial program for weight loss based on a point system, meal replacements, and counseling. The dietary composition is akin to low-fat or moderate-fat and low-carbohydrate diets, depending on the variant used.
Harvard?says?the?Strength of Evidence is: Moderate
Diet#18
Mayo Clinic Diet - Weight Loss Diet
It is a balanced meal plan focused on fruits, vegetables, whole grains, and healthy fat.
Harvard?says the Strength of Evidence is: Moderate.
Diet#17
领英推荐
Time Restricted Eating - Intermittent Fasting
Time-restricted eating is a?form of fasting at a specific time during the day in which consumption of food is limited or compressed. People who practice time-restricted eating typically during an 8- to 12-hour daytime window and fast during the remaining 12 to 16 hours.
Harvard?says?the?Strength of Evidence is: Moderate
Diet#16
VB6, vegan before 6 pm - Plant Forward Diet
This diet does not allow animal products, sugar, white flour, white rice, pasta, or processed foods before 6 pm.
Harvard?says?the?Strength of Evidence is: Moderate
Diet#15
Flexitarian – Plant Forward Diet
Mostly a vegan diet that is flexible but allows 'flexibility' for eating some animal products.
Harvard?says?the?Strength of Evidence is: Moderate
Diet#14
Vegetarian - Plant Forward Diet
This diet primarily excludes meat and seafood (animals). Allows dairy, eggs, honey, and processed foods.
Harvard?says the Strength of Evidence is: Moderate
Diet#13
Vegan – Plant Forward Diet
This diet excludes all animal products, seafood (animals), and all products made from/with animals and allows processed foods.
Harvard?says the Strength of Evidence is: Moderate
Diet#12
Atkins - Low-Carb Diet
It restricts carbohydrates and encourages eating more protein and fat.
Harvard?says the Strength of Evidence is: Moderate
Diet#11
Portfolio Diet – Diet to fight disease
It is designed to lower your cholesterol levels?by including more soy protein, plant sterols, nuts, and soluble fiber in your diet.
Harvard?says the Strength of Evidence is: Moderate
Diet#10
Anti-inflammatory Diet - Diet to fight disease
An anti-inflammatory diet?favors fruits and vegetables, foods containing omega-3 fatty acids, whole grains, lean protein, healthy fats, and spices – created by Harvard-educated Dr. Andrew Weil.
Harvard?says the Strength of Evidence is: Moderate
Diet#9
Gluten-Free Diet - Diets to fight disease
A gluten-free diet is a nutritional plan that strictly excludes gluten, a mixture of proteins found in wheat and barley, rye, and oats.?It is potentially lifesaving for those with celiac disease.
Harvard?says the Strength of Evidence is: Strong.
Diet#8
Low FODMAP - Diets to fight disease
The low FODMAP diet is a temporary eating plan that's very restrictive.?This diet is designed to help people with irritable bowel syndrome (IBS)?and/or small intestinal bacterial overgrowth (SIBO). It restricts onions, peaches, beans, lentils, dairy, and nuts.
Harvard?says?the?Strength of Evidence is: Strong
Diet#7
Volumetric Diet - Weight Loss DietThe Volumetric Diet is an eating plan to?promote weight loss?by having you fill up on?low-calorie, nutrient-dense foods. It prioritizes foods with a high-water content and low-calorie density, such as?low-starch vegetables and whole grains. It also limits processed foods but allows lean meat.
Harvard?says?the?Strength of Evidence is: Strong
Diet#6
TLC Diet - Diets to fight Disease
1980 US Health Department's program to?lower cholesterol. Diet of less than 7% calories from saturated fats and?dietary cholesterol below 200mg daily. All food groups allowed.
Harvard?says the Strength of Evidence is: Strong
Diet#5
DASH Diet - Diets to fight disease
'Dietary Approaches to Stop Hypertension. The DASH diet is?rich in vegetables, fruits, and whole grains. It includes fat-free or low-fat dairy products, fish, poultry, beans, and nuts.?Limits sodium intake to 1500-2300 mg a day.
Harvard?says the Strength of Evidence is: Strong
Diet#4
Mediterranean Diet - Traditional Regional Diet
Regional Diet, traditional cuisines of Greece, Italy, and other countries that border the Mediterranean Sea.?It is high in vegetables, fruits, legumes, nuts, beans, cereals, grains, and unsaturated fats such as olive oil. It usually includes?low amounts of meat and dairy foods.
Harvard?says the Strength of Evidence is: Strong
Diet#3
MIND Diet - Diets to fight Alzheimer's
Hybrid of the?Mediterranean and DASH?diet to fight Alzheimer's Disease.?Rich in whole plant-based foods. Limits processed foods.?Heavy in leafy green vegetables and berries. Fish are allowed once or more per week.
Harvard?says the Strength of Evidence is: Strong
Diet#2
Nordic Diet - Traditional Regional Diet
A restricted diet of the Nordic region. Primarily recommends?whole foods,?leafy green vegetables, root vegetables, fruits, and whole grains (such as oats and barley) and includes freshwater fish.?It limits the consumption of red meat, dairy, sugars, and processed foods.
Harvard?says the Strength of Evidence is: Strong
Diet#1
Ornish Diet - Diets to fight disease
A low-fat diet, whole foods plant-based, limits processed food, and less than 10% calories from refined carbs, egg whites, and nonfat milk.?It avoids all meat, including seafood.?It was created by Dr. Dean Ornish of the University of California to fight heart disease.
Harvard says the Strength of Evidence is: Strong
PART B 7030 Jessica's Observations
1. Intermittent Fasting Diets
A decade ago, advocates of intermittent fasting were male personal trainers (mostly US Americans) selling e-books on their blogs, citing very early research that was primarily conducted on lab rodents.
Most of the research on?an alternate-day fasting diet?is in rats.?"…but humans aren't rats", says the Harvard report. The few studies done in humans are very short in duration—even as fast as one day—and have conflicting results on health markers like blood sugar, cholesterol, and triglyceride levels.
For modified alternate-day fasting, current research fails to show that modified fasting is any better for metabolic health than simply keeping calories in check daily.
2. Diets for Fighting Diseases?
These diets were created to fight certain diseases and likely have solid research-based evidence.?The Ornish diet, a diet that excludes all animal meat, was designed to treat heart diseases,?the DASH diet?to fight blood pressure,?the TLC diet?to reduce blood cholesterol levels,?Gluten Free Diet?to fight celiac disease (a digestive and autoimmune disorder that can damage your small intestine) and the?Low FODMAP Dietto fight IBS (Irritable Bowel Syndrome, a condition that affects the digestive system and causes symptoms like stomach cramps, bloating, diarrhea and constipation).
However, Harvard notes that there is?no evidence that avoiding gluten is healthful for people who do not have celiac disease?or non-celiac gluten/wheat sensitivity. Avoiding gluten may lower your intake of crucial nutrients. Additionally, avoiding gluten-containing whole grains may reduce your fiber intake unless you introduce other food sources of fiber.
3. Traditional Diets?
The traditional?Mediterranean diet?is characterized?by the high consumption of vegetables, fruits, legumes, and whole or minimally processed grains.
The primary fat is olive oil, used to cook and dress the abundant vegetables and legumes. Grains are whole or in the form of fermented sourdough bread or pasta cooked al dente (cooked to be slightly firm when bitten), which lowers the glycemic index (and low glycemic index is better for health, we shall discuss this in upcoming parts of the series). Another critical factor is that?meat?is restricted to maybe?two to three times per month, and there is low consumption of dairy products.
The?Nordic diet?is based on?whole and minimally processed foods?and is high in fiber and heart-healthy omega-3 fats. Observational studies suggest a reduced risk of heart attack, and clinical studies show possible benefits for lowering blood pressure, cholesterol, blood sugar, and inflammation.
4. Plant Forward Diets?(Vegan, Raw Food, Vegetarian, Flexitarian, and others)?
Only some clinical and observational research suggests that plant-forward diets may reduce heart disease, type 2 diabetes, and cancer risk. The report considers these diets somewhat "restrictive" in terms of choices. Since B12 is made only by bacteria and not available in plants, it recommends taking B12 supplements for those on the?Vegan Diet.
Another important highlight is that?processed food, such as meat substitutes as a primary protein source for plant-forward diets, is not healthful. It also says?that plant-based dairy alternatives are low in protein and high in sugar.
The report notes?that plant-forward diets require much preparation, and meal planning is much work?to ensure enough nutrition each day.
Dining out is problematic, according to the report, as these diets, especially the vegan/vegetarian diet, are not mainstream?in most parts of the world. Also, the restrictive nature of these diets makes them a poor choice for individuals recovering from eating disorders or those at risk for eating disorders.
PART C 7030?Jessica's Comments
Though most Intermittent Fasting Diets are weak in evidence,?Time Restricted Intermittent Fasting?has some clinical research to support it, suggesting that this eating pattern?may reduce chronic disease risk. But few trials exist, and they suggest restricting eating to daytime hours is?good for metabolic health. However,?women must be careful in limiting calories and time-restricted eating as it can negatively affect hormone levels.
It is unclear why the?Okinawa Diet, which is similar in principles to the Mediterranean and Ornish, received a 'weak' in the evidence. The report notes that it cannot?determine how much of their benefits (primarily longevity) can be attributed to diet vs. genetic makeup.
The?Portfolio Diet?(essentially a vegan diet with a specific intake of nutrients created to lower cholesterol),?but research does not show evidence that 50g of soy protein a day would reduce cholesterol. Hence, only an average score.
For the?Raw Food Diet?and the Raw Vegan Diet (a subsect of the Raw Food Diet), there is no science to support the idea that we should not heat any of our food above 40 degrees C and hence has a 'non-existent' rating. One study found that people following a raw diet for an extended period have an?increased risk of low bone mass and lack sufficient protein, calcium, and vitamin D.
Surprisingly,?the Harvard?report?failed to acknowledge or account for the Chinese Buddhist Vegan Diet and the Indian Vegetarian diet, which have thousands of years of history and observational evidence like the Nordic and Mediterranean diets. There is a gap in the ability to study diets far from Boston (Harvard?location). However, given the resources and reach of Harvard, this should not have been an issue.
PART D: 7030 Nutritionist's Conclusion What is a healthy diet??
While details may vary from diet to diet,?Harvard agrees that all healthy diets, and the ones that show strong evidence, such as the Ornish diet & Mediterranean diet, have these five principles in common. All of these are geared towards a Plant Forward Eating pattern:
1. Lots of plants for high nutrition, low calories
Plant foods—vegetables, fruits, legumes, whole grains, nuts, and seeds—offer a wealth of vitamins, minerals, fiber, and essential plant chemicals (phytochemicals). They have benefits, including antioxidant, anti-inflammatory, and even anti-cancer activity. Many plant foods are high in nutrients and relatively low in calories.
2. Adequate protein. Plant protein is a good choice
People who chose plant proteins tend to have lower risks for chronic diseases—plant protein sources - beans, lentils, soy foods, nuts, and seeds.
PS: Though?the Harvard?report adds fish as an ideal protein source, not all fish sources are sustainable. Farm-raised fish?can be slightly higher in omega-3 fatty acids, presumably due to the farms' fortified feed. Some studies have shown how farm-raised varieties can be taller in contaminants. It is important to note that mercury can be found in both farm-raised and wild-caught seafood due to industrial pollution that finds its way into lakes, rivers, and oceans. Large predatory fish have the most mercury.
3. Whole Foods and Minimally Processed Food
For the healthiest diet, rely as much as possible on whole foods - unprocessed foods, such as broccoli, apples, and almonds. And minimally processed foods- such as white rice, bread, etc. Processing tends to strip away nutrients while adding extra fats, sugars, and sodium.
4. Limited saturated fats, added sugars, and sodium
Dietary Guidelines for Chinese Residents (2016) states that saturated fats and added sugars should each comprise less than 10% of daily calories, and daily salt consumption should be lower than 2300 mg. (An average American resident consumes more than 3,400 milligrams per day.) An example for a high saturated fat food is lard.
5. Balanced Nutrition
To meet nutrient needs, choosing various nutrient-dense foods across and within all food groups, vegetables, fruits, healthy protein sources, whole, unprocessed grains, healthy fats, and oils is essential.
PS: Harvard quotes "dairy" as a food group. However, they still recognize that nutrients found in dairy, such as calcium, can be balanced from other plant sources.
70/30 is launching the series A round of funding for scaling-up production of the mycelium protein, growing the research and development team, and bringing out exciting new products created for the Chinese consumer!
References:
[1] https://www.health.harvard.edu/diet-and-weight-loss/the-diet-review
[2] https://www.health.harvard.edu/blog/move-over-mediterranean-a-vegetarian-diet-is-equally-good-for-health-201306056352
[3] https://chhs.source.colostate.edu/author/krnc/
[4] https://www.thendobetter.com/arts/2020/1/25/fake-meat-origins-with-chinese-monks?format=amp
[5] https://www.health.harvard.edu/heart-health/the-dairy-dilemma
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70/30 Food Tech makes functional plant and mycelium-based ready meals and develops its biomass protein. 70/30's philosophy is that 70% of what we eat should be made up of a variety of plant-based whole foods, and 30% of our food should be fun. Founded in 2020 by F&B consultants working in China's plant-based sector, the startup makes functional meal plans for the busy white-collar professionals living in tier 1 cities of the country. Its mission is to improve human health and battle climate change by making healthy food convenient, accessible, and affordable for all.?