This week’s article may push a few buttons.  

Eating strategies are quite unique and highly personal for each of us.  We have traditions involving food, religious observances, personal preferences, health issues and needs, financial influences, cultural influences, and access issues.  The point of this article is not to tell you what diet to follow - there is enough of this out there already.  My aim is to present a scientifically based review and discussion of some of the more prominent eating strategies out there.

I also want to emphasize the fact that there is no one-size-fits-all approach.  No diet, fad or otherwise, will be perfect for everyone.  We also need to remember that food is about more than its biological functions and that food can be a wonderful source of pleasure and community.  When we focus too much on finding the “best diet for xyz,” we forget that food is part of life.  We are all trying to find the lifestyle (including food) that best supports us in living a life we want to be in.  When concerns about food begin to dominate life, the risk of developing or relapsing into an eating disorder increases and change is needed.  Mental healthcare, compassionate nutritional advice from trained and dedicated professionals, and the support of family and friends are needed in these situations.  

If you find yourself regularly stressed out over food, please reach out for help. 

An Overview of Popular Diet Categories: 

When looking at a new potential food plan to follow, one should be able to determine which category of diet it falls into.  This will help you as you research the scientific evidence for any claims being made.

Low Carbohydrate Diets: 

According to the Mayo Clinic, “A low-carb diet limits carbohydrates — such as those found in grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat. Many types of low-carb diets exist. Each diet has varying restrictions on the types and amounts of carbohydrates you can eat.” (1)

A few examples include: 

• Atkins

• South Beach

• Ketogenic

• Whole30/Paleo

Claims: 

• Increased weight loss

• Prevention or treatment of diabetes/insulin resistance. 

Evidence: 

• A 2018 article in the European Journal of Nutrition showed weight loss and improved insulin sensitivity along with decreased hemoglobin A1c levels in people who were able to maintain a low carbohydrate diet.  However, increased levels of blood fats and issues within the cardiovascular system were also seen.  Adherence to this way of eating long-term was low, and long-term safety and efficacy (past 2 years) has not been determined. (2)

• A meta analysis of 9 randomized controlled trials also showed favorable outcomes in relation to blood sugar but not weight loss. (3)

• Another meta analysis of 13 randomized controlled trials showed beneficial outcomes in very low carbohydrate diets (10% or fewer calories from carbohydrates) with reductions in body fat in obese individuals, but not as much success with low carbohydrate diets (40% or fewer calories from carbohydrates). (4)

• When it comes to ketogenic diets, most of the research is in the control of drug-resistant epilepsy.

Potential Hazards: 

• Kidney damage due to high protein content

• Kidney stones (5)

• Digestive issues

• Nutrient deficiencies especially Calcium, Potassium, Vitamin D, Magnesium, Phosphorus, and fiber (6)

• Potential for low blood sugar crashes

• Increased risk of osteoporosis (7)

• Increased risk of chronic illness/death (8)

Low Fat Diets: 

In low fat diets, the goal is to reduce the amount of fat consumed in the diet.  These diets tend to include lean meats like poultry and fish, low fat dairy products, fruits and vegetables, and grain products.  Red meat, oils, butters, nuts, seeds, and full fat dairy are typically avoided. 

A few examples include: 

• The Mayo clinic diet

• The Ornish diet

• The Macrobiotic diet

• The TLC diet

Claims: 

• Weight loss

• Improved Cardiovascular Health

Evidence: 

• A meta analysis of 53 randomized controlled studies did not show an increase in weight loss when compared to other weight loss strategies. (9)

• Another meta analysis of 32 randomized controlled studies found no significant improvement in cardiovascular health between low and high fat diets. (10)

Potential Hazards: 

• Nutrient depletion especially of the fat soluble vitamins: ADE and K

Vegetarian/Vegan Diets: 

Vegetarian diets do not include meat but may include dairy and egg products.  Some follow a pescatarian diet, allowing fish but no meat from other animal sources.  A vegan diet excludes all animal products.  These diets can be low fat, low carb, or neither. 

A few examples include: 

• Flexitarian (mostly vegetarian but allows occasional meat)

• Vegetarian Mediterranean diet

• Vegan diet

Claims: 

• Reduced risk of cardiovascular disease.

• Better digestive health including reduced risk of colon cancer.

• Reduced risk of diabetes. 

• Better blood pressure control.

• Longer life. 

Evidence: 

• A 2017 meta analysis of 14 randomized controlled studies showed a decreased incidence of diabetes amongst vegetarians especially in Western countries. (11)

• Another 2017 meta analysis of 86 cross sectional and 10 cohort prospective studies showed a significant reduction in cardiovascular disease (25%) and all cancers (8%) from a vegetarian diet and an additional total cancer reduction (15%) for those on a vegan diet. (12)

• If weight loss is the goal, a meta analysis of 12 studies done in 2016 showed that a vegetarian diet is associated with much better weight loss outcomes than non-vegetarian diets. (13)

• For those with inflammatory disorders, a vegetarian diet is associated with lower levels of C reactive protein. (14) (15)

• We also see reduced cholesterol levels associated with vegetarian diets. (16)

• Blood pressure is lower amongst those consuming a vegetarian diet. (17)

• While not the best overall diet (the Mediterranean diet claims this title) for reducing blood sugar among diabetic patients, a vegetarian diet was found to be significantly associated with better blood sugar control, especially with fasting blood sugar when compared to 9 other diets. (18)

Potential Hazards: 

• Nutrient deficiency especially Vitamin B12 and iron

• Osteoporosis/osteopenia among vegans, due to potential deficiency of calcium. 

Point/Calorie Counting Diets/Prepackaged “medical foods”: 

These diets focus on guiding customers primarily in weight loss.  They can be any combination of the above diet plans but their main focus is on how many calories are consumed and how this breaks down by fat, carbohydrate, and protein.  Often there is a support system built-in and are time-saving, but often these diets are quite expensive financially. 

A few examples include: 

• Weight Watchers

• Jenny Craig

• Medifast

Claims: 

• Weight loss

Evidence: 

• After 1 year of following the Weight Watchers diet, the average weight loss was 6.5 pounds (3 Kg). (19)

• Weight loss systems with support show more weight loss than nutritional education alone. (20) 

Potential Hazards: 

• Low compliance - many people could not continue following the diet.

• High monetary cost. 

• Hormone disruption with programs containing high amounts of processed soy.

• Digestive upset with packaged foods.

Detoxification Diets: 

These diets focus on weight loss and improved health through a detoxification lens.  They are often partnered with quite a few supplements, some medical foods, and often laxatives.  They are also often very low in calories which promotes weight loss over the short term, but they are not sustainable. 

A few examples include: 

• Juice fasting

• Water fasting

• Raw foods diet

• Soup diet

• Grapefruit diet

Claims: 

• Weight loss

• Reversal of illness

• Removal of  amassed toxins in the body

• Improved mental function

Evidence: 

• I could not find a single meta analysis on this topic.

Potential Hazards: 

• Low blood sugar events.

• Fatigue

• Mental confusion

• Nutrient deficiencies from withholding food or from supplements such as activated charcoal or clays binding nutrients and carrying them unabsorbed through the digestive system.

• Disruption of digestive function including creating a dependence on laxatives in order to have a bowel movement. 

• Constipation from lack of fiber intake

• Diarrhea from laxative use

• Electrolyte imbalances creating nervous system and cardiovascular damage either from drinking water without electrolytes or through copious amounts of diarrhea

• Mental health crisis events

• Spreading a false belief that our bodies are dirty or toxic and need outside intervention in order to maintain normal metabolic detoxification processes.

• Being misled and tricked out of your resources and time. 

The Mediterranean Diet: 

Hands down, the diet that is best supported through research is the Mediterranean diet.  There are different versions that have been popularized such as a Vegetarian or Vegan Mediterranean diet, a Paleo Mediterranean diet, an Autoimmune Mediterranean diet, etc.  However, there is no standardized Mediterranean diet. 

Each year, U.S. News and World reports on the best diets of the year, and a Mediterranean diet has won their top best diet overall year after year.  2021 is no exception with the Mediterranean diet ranking in the top spot for the following categories: (21)

• Best overall diet

• Best plant-based diet

• Best heart-healthy diet

• Best diabetes diet

• Best diet for healthy eating

• Easiest diet to follow

According to the American Heart Association, A Mediterranean diet includes: 

“plenty of fruits, vegetables, bread and other grains, potatoes, beans, nuts and seeds; olive oil as a primary fat source; and dairy products, eggs, fish and poultry in low to moderate amounts.

Fish and poultry are more common than red meat in this diet. It also centers on minimally processed, plant-based foods. Wine may be consumed in low to moderate amounts, usually with meals. Fruit is a common dessert instead of sweets.“ (22)

Claims: 

• Reduced risk of cardiovascular disease.

• Weight loss. 

• Improved overall health. 

• Improved mental health. 

• Prevention of Type 2 diabetes.

• Anti-inflammatory in nature so helps people with arthritis and other inflammatory conditions. 

• Cancer protection. 

Evidence: 

• Diminished incidence of colorectal cancer. (23)

• Improved function in the lining of blood vessels showing promise in the prevention of cardiovascular disease. (24)

• Reduced incidence of diabetes in those with pre-diabetes when switching to a Mediterranean diet. (25)

• Diminished incidence of stroke in those adhering to a Mediterranean diet. (26)

• Reduced incidence of chronic kidney disease (CKD). (27)

• No effect on incidence of prostate cancer. (28)

• Possible reduction in rates of mortality from all causes. (29)

• Possible small reduction in rates of depression. (30)

Potential Hazards: 

• None identified. 

A Summary:

As you can see the evidence is pretty strong for both the Mediterranean and vegetarian/vegan diets when it comes to health benefits across the board.  Low carb diets tend to outperform low fat diets when it comes to weight loss, but this also creates higher cholesterol levels.  Detox diets are filled with bogus claims, misleading ideas about how our bodies function, and potentially dangerous side effects.  Programs like Weight Watchers do show small amounts of weight reduction after a year of adherence, but are not associated with large and well maintained amounts of weight loss.

There are other medical diets that have not been covered here such as a Low FODMAP diet for IBS or IBD.  We also haven’t covered the DASH diet for blood pressure management.  If you have a diagnosed medical condition and have been recommended a specific medical diet by your doctor, ask for the research, or read the studies yourself, and give it some real consideration. 

Also, you may have noticed that any eating strategy that eliminates any food group can and often leads to nutrient deficiencies or insufficiencies.  As always, a great way to look into this is to track what you eat using a program that looks at your micronutrient intake such as Wholesome or Cronometer.  Then you can research supplements or turn to your healthcare team for advice on how to fill in those nutritional gaps.  

Applications: 

Michael Pollen said it best, “Eat food.  Not too much.  Mostly plants.”

There are so many ways to eat, and there has been some helpful research done in the field of nutrition.  Many of the most popular diets out there have little to no well designed and replicated research done on them, but you can look.  My preferred method is to look directly at the research using PubMed.  I like to look at meta analyses, as these look at multiple studies and compare them to get a better understanding.  When we are looking at scientific data, we want information that has been verified and reproduced in subsequent studies.  When you hear about the “latest research” on the news, they are most likely reporting from a single study; this is why we hear such conflicting information over and over.  While these news reports give the impression that science contradicts itself, what we are really seeing is a rush to report sensational claims that have yet to be retested or a single study whose results are different from other studies.  Scientists know that one positive study doesn’t prove something to be effective, that’s why you commonly see calls for more and better research in the conclusion of published studies. 

Also, be wary of any claims about something being “scientifically proven”. Science doesn’t set out to prove things it either disproves things or provides supporting evidence. Something can be “supported by science” or “validated by science” but not proven. Be wary of slick sales pitches!

What I Recommend Based on the Best Available Evidence:

I advocate for people to follow a whole-foods, plant-based diet.  This means eating food that looks like it was grown, not made in a lab.  It means eating whole grains, beans, fruit, vegetables, seeds, nuts, herbs, and spices daily.  It means occasionally eating animal products if desired.  It also means indulging in chocolate cake or ice cream as an occasional treat, but not regularly.  It can mean working with a meal delivery service, cooking most or all of your own meals, eating out selectively, or a combination approach.  It’s your life, and you are the only one living it, so you get to make those choices. 

To make life easier in our home where we cook almost all of our own food, we invested in an instant pot, and we use that appliance daily.  We also regularly use a blender or food processor, cast iron skillets, and a coffee grinder for nuts and seeds.  We choose one meal that we just can’t get enough of (burritos/burrito bowls right now) and eat this a few times a week.  This gives us consistency and makes meal planning easier.  It also makes getting more creative in the kitchen more fun, as we don’t have to do it every night.  

So, don’t get too wrapped up in fantastical claims about fad diets.  Find a way of eating that incorporates healthy plant-based foods you enjoy and is sustainable for you in the long run.  And, when you hear about the latest and greatest new diet, take a few minutes to look at what the research says.  Don’t let someone trying to sell you something interpret the research for you or tell you stories in leu of sharing research. Stories are powerful but they only tell you what worked for one person, scientific research looks at groups of people, is designed to look at one thing at a time, and benefits from the review of other professionals in the field before it’s published. 

Next Week: 

For our first article of February, I will explore the concept of nutrient depletion.  We will talk about medications that deplete nutrients, how to look your medications up, and how to address what you find. 

To our health!

References

1. “Low-carb diet: Can it help you lose weight?” https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/low-carb-diet/art-20045831

2. Brouns F. Overweight and diabetes prevention: is a low-carbohydrate-high-fat diet recommendable? Eur J Nutr. 2018 Jun;57(4):1301-1312. doi: 10.1007/s00394-018-1636-y. Epub 2018 Mar 14. Erratum in: Eur J Nutr. 2019 Apr 16;: PMID: 29541907; PMCID: PMC5959976.

3. Meng Y, Bai H, Wang S, Li Z, Wang Q, Chen L. Efficacy of low carbohydrate diet for type 2 diabetes mellitus management: A systematic review and meta-analysis of randomized controlled trials. Diabetes Res Clin Pract. 2017 Sep;131:124-131. doi: 10.1016/j.diabres.2017.07.006. Epub 2017 Jul 8. PMID: 28750216.

4. Hashimoto Y, Fukuda T, Oyabu C, Tanaka M, Asano M, Yamazaki M, Fukui M. Impact of low-carbohydrate diet on body composition: meta-analysis of randomized controlled studies. Obes Rev. 2016 Jun;17(6):499-509. doi: 10.1111/obr.12405. Epub 2016 Apr 5. PMID: 27059106.

5. Carnauba RA, Baptistella AB, Paschoal V, Hübscher GH. Diet-Induced Low-Grade Metabolic Acidosis and Clinical Outcomes: A Review. Nutrients. 2017 May 25;9(6):538. doi: 10.3390/nu9060538. PMID: 28587067; PMCID: PMC5490517.

6. Zupec-Kania B, Zupanc ML. Long-term management of the ketogenic diet: seizure monitoring, nutrition, and supplementation. Epilepsia. 2008 Nov;49 Suppl 8:23-6. doi: 10.1111/j.1528-1167.2008.01827.x. PMID: 19049580.

7. Simm PJ, Bicknell-Royle J, Lawrie J, Nation J, Draffin K, Stewart KG, Cameron FJ, Scheffer IE, Mackay MT. The effect of the ketogenic diet on the developing skeleton. Epilepsy Res. 2017 Oct;136:62-66. doi: 10.1016/j.eplepsyres.2017.07.014. Epub 2017 Jul 26. PMID: 28778055.

8. Fung TT, van Dam RM, Hankinson SE, Stampfer M, Willett WC, Hu FB. Low-carbohydrate diets and all-cause and cause-specific mortality: two cohort studies. Ann Intern Med. 2010 Sep 7;153(5):289-98. doi: 10.7326/0003-4819-153-5-201009070-00003. PMID: 20820038; PMCID: PMC2989112.

9. Tobias DK, Chen M, Manson JE, Ludwig DS, Willett W, Hu FB. Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis. Lancet Diabetes Endocrinol. 2015 Dec;3(12):968-79. doi: 10.1016/S2213-8587(15)00367-8. Epub 2015 Oct 30. PMID: 26527511; PMCID: PMC4667723.

10. Schwingshackl L, Hoffmann G. Comparison of effects of long-term low-fat vs high-fat diets on blood lipid levels in overweight or obese patients: a systematic review and meta-analysis. J Acad Nutr Diet. 2013 Dec;113(12):1640-61. doi: 10.1016/j.jand.2013.07.010. Epub 2013 Oct 17. PMID: 24139973.

11. Lee Y, Park K. Adherence to a Vegetarian Diet and Diabetes Risk: A Systematic Review and Meta-Analysis of Observational Studies. Nutrients. 2017 Jun 14;9(6):603. doi: 10.3390/nu9060603. PMID: 28613258; PMCID: PMC5490582.

12. Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017 Nov 22;57(17):3640-3649. doi: 10.1080/10408398.2016.1138447. PMID: 26853923.

13. Huang RY, Huang CC, Hu FB, Chavarro JE. Vegetarian Diets and Weight Reduction: a Meta-Analysis of Randomized Controlled Trials. J Gen Intern Med. 2016 Jan;31(1):109-16. doi: 10.1007/s11606-015-3390-7. PMID: 26138004; PMCID: PMC4699995.

14. Haghighatdoost F, Bellissimo N, Totosy de Zepetnek JO, Rouhani MH. Association of vegetarian diet with inflammatory biomarkers: a systematic review and meta-analysis of observational studies. Public Health Nutr. 2017 Oct;20(15):2713-2721. doi: 10.1017/S1368980017001768. Epub 2017 Aug 24. PMID: 28836492.

15. Craddock JC, Neale EP, Peoples GE, Probst YC. Vegetarian-Based Dietary Patterns and their Relation with Inflammatory and Immune Biomarkers: A Systematic Review and Meta-Analysis. Adv Nutr. 2019 May 1;10(3):433-451. doi: 10.1093/advances/nmy103. PMID: 30947338; PMCID: PMC6520040.

16. Yokoyama Y, Levin SM, Barnard ND. Association between plant-based diets and plasma lipids: a systematic review and meta-analysis. Nutr Rev. 2017 Sep 1;75(9):683-698. doi: 10.1093/nutrit/nux030. PMID: 28938794; PMCID: PMC5914369.

17. Yokoyama Y, Nishimura K, Barnard ND, Takegami M, Watanabe M, Sekikawa A, Okamura T, Miyamoto Y. Vegetarian diets and blood pressure: a meta-analysis. JAMA Intern Med. 2014 Apr;174(4):577-87. doi: 10.1001/jamainternmed.2013.14547. PMID: 24566947.

18. Schwingshackl L, Chaimani A, Hoffmann G, Schwedhelm C, Boeing H. A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus. Eur J Epidemiol. 2018 Feb;33(2):157-170. doi: 10.1007/s10654-017-0352-x. Epub 2018 Jan 4. PMID: 29302846; PMCID: PMC5871653.

19. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005 Jan 5;293(1):43-53. doi: 10.1001/jama.293.1.43. PMID: 15632335.

20. Gudzune KA, Doshi RS, Mehta AK, Chaudhry ZW, Jacobs DK, Vakil RM, Lee CJ, Bleich SN, Clark JM. Efficacy of commercial weight-loss programs: an updated systematic review. Ann Intern Med. 2015 Apr 7;162(7):501-12. doi: 10.7326/M14-2238. Erratum in: Ann Intern Med. 2015 May 19;162(10):739-40. PMID: 25844997; PMCID: PMC4446719.

21. https://health.usnews.com/best-diet/mediterranean-diet

22. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/mediterranean-diet

23. Zhong Y, Zhu Y, Li Q, Wang F, Ge X, Zhou G, Miao L. Association between Mediterranean diet adherence and colorectal cancer: a dose-response meta-analysis. Am J Clin Nutr. 2020 Jun 1;111(6):1214-1225. doi: 10.1093/ajcn/nqaa083. PMID: 32359135.

24. Shannon OM, Mendes I, Köchl C, Mazidi M, Ashor AW, Rubele S, Minihane AM, Mathers JC, Siervo M. Mediterranean Diet Increases Endothelial Function in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Nutr. 2020 May 1;150(5):1151-1159. doi: 10.1093/jn/nxaa002. PMID: 32027740.

25. Uusitupa M, Khan TA, Viguiliouk E, Kahleova H, Rivellese AA, Hermansen K, Pfeiffer A, Thanopoulou A, Salas-Salvadó J, Schwab U, Sievenpiper JL. Prevention of Type 2 Diabetes by Lifestyle Changes: A Systematic Review and Meta-Analysis. Nutrients. 2019 Nov 1;11(11):2611. doi: 10.3390/nu11112611. PMID: 31683759; PMCID: PMC6893436.

26. Saulle R, Lia L, De Giusti M, La Torre G. A systematic overview of the scientific literature on the association between Mediterranean Diet and the Stroke prevention. Clin Ter. 2019 Sep-Oct;170(5):e396-e408. doi: 10.7417/CT.2019.2166. PMID: 31612199.

27. Bach KE, Kelly JT, Palmer SC, Khalesi S, Strippoli GFM, Campbell KL. Healthy Dietary Patterns and Incidence of CKD: A Meta-Analysis of Cohort Studies. Clin J Am Soc Nephrol. 2019 Oct 7;14(10):1441-1449. doi: 10.2215/CJN.00530119. Epub 2019 Sep 24. PMID: 31551237; PMCID: PMC6777603.

28. Cheng S, Zheng Q, Ding G, Li G. Mediterranean dietary pattern and the risk of prostate cancer: A meta-analysis. Medicine (Baltimore). 2019 Jul;98(27):e16341. doi: 10.1097/MD.0000000000016341. PMID: 31277188; PMCID: PMC6635247.

29. Soltani S, Jayedi A, Shab-Bidar S, Becerra-Tomás N, Salas-Salvadó J. Adherence to the Mediterranean Diet in Relation to All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. Adv Nutr. 2019 Nov 1;10(6):1029-1039. doi: 10.1093/advances/nmz041. PMID: 31111871; PMCID: PMC6855973.

30. Shafiei F, Salari-Moghaddam A, Larijani B, Esmaillzadeh A. Adherence to the Mediterranean diet and risk of depression: a systematic review and updated meta-analysis of observational studies. Nutr Rev. 2019 Apr 1;77(4):230-239. doi: 10.1093/nutrit/nuy070. Erratum in: Nutr Rev. 2019 Jun 1;77(6):454. PMID: 30726966.