Study Review: Heterogeneous metabolic adaptation of C57BL/6J mice to high-fat diet

Study: http://www.physiology.org/doi/pdf/10.1152/ajpendo.00332.2001

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
"Normal Chow"	60%	12%	28%
"High Fat"	<1%	72%	28%

Historical chart shows the high fat diet increased weight gain, glucose, insulin, and AUCs.

Criteria	Score	Comments
One Constant Macro	****	Protein matches. Point off for no food source.
Constant Nutrients + Fiber	*	Not documented.
Number of animals per diet	*****	15-25
Length of Study	**	9 months
Funding Bias	*****	Grant by Swiss National Science Foundation and the Juvenile Diabetes Foundation International
Total	3.4	Fair Quality Study

Study Review: Differential effects of saturated versus unsaturated dietary fatty acids on weight gain and myocellular lipid profiles in mice

Study: https://www.nature.com/articles/nutd20117.pdf

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
D12450B	70%	10%	20%
D12451	35%	45%	20%

The D12451 diet was customized with varying types of fat.

Historical charts show body weight lower for Low Fat Diet, and High Fat Cocoa Butter diet. Body weight is highest for Palm Oil, then Olive Oil, then Safflower Oil.

One Constant Macro	*****	Protein does not change at all.
Constant Nutrients + Fiber	****	Vitamins and Minerals stayed the same. Diets were customized beyond standard datasheet availability. Unable to determine if the custom diets had modified carb types.
Number of animals per diet	**	6 mice per diet. (5 diets total)
Length of Study	*	8 weeks
Funding Bias	**	Grant from "Top Institute Food and Nutrition", which partners with Kellogg's, Nestle, Pepsico.
Total	2.8	Poor Quality Study

Study Review: Diet-induced type II diabetes in C57BL/6J mice

Study: https://www.academia.edu/13414214/Diet-induced_type_II_diabetes_in_C57BL_6J_mice

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
Purina Rodent Chow	58%	13.5%	28.5%
High Fat	26.7%	35.8%	14.9%

Charts show blood glucose, body weight, and insulin levels where all worse for mice on the "high carb high fat" diet.

One Constant Macro	*	All macros change by more than 10%.
Constant Nutrients + Fiber	*	All three macros changed significantly. They incorrectly called the diet "High Carb High Fat". The "Standard Diet's" carbs where "Complex Carbohydrates" and higher fiber, while the "High Carb High Fat" carbs where "simple carbohydates" and low fiber.
Number of animals per diet	*****	Although multiple mice breeds were used, there were 18 - 20 mice per diet.
Length of Study	**	24 weeks
Funding Bias	*****	Grants from various health based organizations. Food industry not involved.
Total	2.8	Poor Quality Study

Study Review: A Low Carbohydrate, High Protein Diet Slows Tumor Growth and Prevents Cancer Initiation

Study: http://cancerres.aacrjournals.org/content/canres/71/13/4484.full.pdf

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
Western 5058	55.2%	21.6%	23.2%
High Protein	15.6%	26.2%	58.2%

Historical charts show blood glucose, body weight, insulin levels, and longevity, where all better in mice that had the low carb diet.

One Constant Macro	***	Fat had a 4.6% difference.
Constant Nutrients + Fiber	**	TestDiet.com did not have the "Western 5058" nor "CHO" nutrition available. Point given since both diets come from the same vendor.
Number of animals per diet	***	10 - 11 animals per diet
Length of Study	*****	2.7 years. Includes the animal's whole life span.
Funding Bias	*****	Grants from various cancer organizations. Food industry not involved.
Total	3.6	Fair Quality Study

Scoring Animal Nutrition Studies

Human studies on food intake, are quite limiting. Human subjects:

• Cannot be controlled or monitored 24 hours a day on their food intake.
• May cheat, intentionally or accidentally, snacking on non-diet foods.
• Prefer a diverse range of foods. They may stop participating in the study simply because they don't like eating the same food all day, every day.
• Expect a diet to be a short term experiment, not a long lifestyle change.

All of these factors make human studies provide poor quality data.

Instead, many studies are done on animals, especially rodents.
Rodents' diets can be controlled and monitored for their entire lifespan.

Although their digestive system may differ from humans', rodents have the ability to get cardiovascular diseases, diabetes, and other forms of metabolic syndrome, allowing us to draw analogs of general causes of such diseases.


Unfortunately, almost all animal studies that I have reviewed, were flawed.

Any setup information that was not discussed in detail, is frequently poorly handled.
Researchers spend much more time examining and discussing the results of the study, rather than making sure their initial setup was well done.

Students are often pushed to write as many papers as possible, leading them to cut the experiments short.
Instead of studying the long term mortality effects of a particular diet, researchers frequently stop the experiment and draw conclusions from data that was as little as 3 weeks long.

As a result, many articles end up being a big waste of grant money, and provide much confusion for the scientific community.
Although animal food intake research has been going on for centuries, with the ongoing conflicts in observations, very few substantial conclusions have been made.


Initially I wanted to write up a post, what would be a "gold standard" article. A study that would be able to overcome the usual conflicting arguments involved in research, and really make a difference in science.
But then I realized I can do something even better..
Inspired by Cornucopia's Egg Scorecard, I decided to dedicate my time to "grading" animal food intake research articles.
I will taking into account factors like: the nutritional intake being similar between the different experimental diets, the length of the experiment, and conflicts of interest from funding bias.

The hope is that over time, if someone emails you a study, you'd be able to look it up on my scorecard, and be able to quickly judge the value of that article.

The permanent link to the list of articles is here:
https://veniaminilmer.blogspot.com/p/animal-studies.html

I am looking for high quality studies to add to the list.
Have a link to a good study? Please send it my way.
Just make sure the article is a free publicly available paper, that involves animal food intake, experimenting with different diets.

Study Review: Changes in Gut Microbiota Control Metabolic Endotoxemia-Induced Inflammation in High-Fat Diet–Induced Obesity and Diabetes in Mice

Study: http://diabetes.diabetesjournals.org/content/diabetes/57/6/1470.full.pdf

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
A04	72.4%	8.4%	19.3%
High Fat	<1%	72%	28%

Criteria	Score	Comments
One Constant Macro	*	Protein changes by 8.7%
Constant Nutrients + Fiber	*	Not Documented
Number of animals per diet	****	13 - 17
Length of Study	*	4 weeks
Funding Bias	****	Grant by various French government organizations. However, there is a questionable "Nutritia Foundation".
Total	2.2	Poor Quality Study

Study Review: Defining high-fat-diet rat models: metabolic and molecular effects of different fat types

Study: http://cancerres.aacrjournals.org/content/canres/71/13/4484.full.pdf

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
Normal	65%	11%	24%
High Fat	36%	45%	19%

Criteria	Score	Comments
One Constant Macro	***	Protein changes by 5%
Constant Nutrients + Fiber	*	Carb Types, Vitamins, Minerals, Fatty Acids, and Amino Acids all changed.
Number of animals per diet	***	"6–12 animals"
Length of Study	**	12 weeks
Funding Bias	*****	Grant provided by Else Kröner-Fresenius Foundation The food industry was not involved.
Total	2.8	Poor Quality Study

Study Review: Metabolic Evidence for Adaptation to a High Protein Diet in Rats

Study: https://academic.oup.com/jn/article-pdf/131/1/91/24019379/4w010100091.pdf

Energy Macro Percent Usage

Diet	Carbs	Fats	Protein
Normal Diet (P14)	75.9%	9.4%	14.7%
High Protein (P50)	38%	9.4%	52%

Charts show food intake and weight gain was slightly lower in the protein based diet than in the carb based diet.

Criteria	Score	Comments
One Constant Macro	*****	Fat did not change.
Constant Nutrients + Fiber	*****	Same Vitamins and Minerals. Carb, Fat, and Protein type stayed the same.
Number of animals per diet	***	8 mice were used per diet.
Length of Study	*	21 days.
Funding Bias	*****	Research was done by the Institut national agronomique Paris Grignon
Total	3.8	Fair Quality Study