For decades, dietary fat has been at the center of health debates. Low-fat dairy has long been considered the healthier option due to its reduced fat, calorie, and cholesterol content. But is it really better for your health? Recent research calls this assumption into question. It may just be time to break up with skim milk and enjoy that glass of whole milk guilt-free.

The low-fat craze

In the 1980s and 1990s, low-fat diets became the big health trend. Experts urged the public to reduce dietary fat in order to lower heart disease risk and maintain a healthy weight—grocery store shelves filled with low-fat and fat-free alternatives, marketed as the healthier option. 

However, this narrative has evolved a bit. Whole-fat foods, especially full-fat dairy products, and healthy oils, have seen a resurgence as new research highlights potential health benefits. Concerns about added sugars and processed ingredients in low-fat products have also fueled this shift. 

So, which is truly healthier: low fat or whole fat? Keep reading to find out!

Understanding dietary fat

Fat is one of the three essential macronutrients, alongside protein and carbohydrates, that make up our diet. Fat plays a critical role in the body by providing energy, supporting cell function, keeping the body warm, helping make hormones, and helping absorb fat-soluble vitamins (A, D, E, K). It is also crucial for proper brain development. 

But not all fat is created equal. Understanding the different types of fats can help clarify their impact on health.

Types of fats:

• Saturated fats: Mostly found in animal products such as meat, dairy, and butter, saturated fats have historically been thought of as unhealthy due to their potential to raise LDL (“bad”) cholesterol, therefore increasing the risk for heart disease. However, recent research suggests the link between saturated fat intake and heart disease is a bit more complex. For example, cheese and yogurt may lower heart disease risk, while red meat has been linked to a higher risk. While saturated fat may increase LDL ("bad") it also appears to increase HDL ("good”) cholesterol, offering a more nuanced health profile.

It also appears that increased saturated fat intake does not directly correlate with increased cholesterol. However, this isn’t to say that diets high in saturated fat are healthy. Studies show that replacing saturated fats with polyunsaturated fats is more beneficial in the long term.

What initially seemed like a simple nutrition topic has become quite complex.

• Unsaturated fats: These are widely considered to be heart-healthy fats. They can be found in nuts, seeds, avocados, and olive oil. There are two types of unsaturated fats:

1. Monounsaturated fats: Found in olive oil, nuts, and avocados.
2. Polyunsaturated fats: Found in fatty fish, flaxseeds, and walnuts, they include omega-3 and omega-6 essential fatty acids, which have various health benefits, including brain, heart, and cognitive health.

• Trans fats: Artificial trans fats are created through hydrogenation, a process that turns liquid oils into solid fats. Some naturally occurring trans fats are created in the gut of some animals. Due to this, foods made from these animals can contain a small percentage of naturally occurring trans fats. Artificial trans fats, primarily partially hydrogenated oils (such as margarine), have been widely criticized and are linked to increased risk of heart disease, type II diabetes, stroke, and inflammation and should be avoided as much as possible. The FDA no longer recognizes partially hydrogenated oils as safe.   

The case for low-fat dairy 

Low-fat dairy contains less saturated fat, has fewer calories, and less cholesterol, making it a suitable option for those sensitive to these components or someone on a low-calorie diet. The American Heart Association recommends using fat-free or low-fat dairy products. 

The case for whole-fat dairy 

Whole milk aids in absorbing fat-soluble vitamins A and D, often fortified in milk. It also supports calcium absorption, which is enhanced by vitamin D.

Studies show that whole-fat dairy can help with weight management.  A long-term study of nearly 20,000 women found that high-fat dairy consumption was linked to an 8% lower risk of weight gain. So, while it may seem counterintuitive, eating full-fat dairy can actually help you to eat less overall.

Research has also linked whole-fat dairy to a lower risk of chronic diseases such as metabolic syndrome, type II diabetes, and infertility. More research is still needed, but one large study found that women who consumed whole-fat dairy had a significantly lower risk of ovulatory infertility (infertility due to an inconsistent menstrual cycle). In one study, researchers found that women who ate more than two portions of low-fat dairy daily had an 85% increase in becoming infertile due to ovulatory disorders compared to women who only ate low-fat dairy once a week.

Other studies show that consuming whole milk lowers the risk of metabolic syndrome. A cluster of risk factors that increases the risk of heart disease, stroke, and type II diabetes. One large meta-analysis, in particular, found that whole-fat dairy products, especially milk and yogurt, may have a protective role in managing key health markers such as blood sugar, cholesterol, and body fat. 

Additionally, one large study found that those who had the highest levels of dairy fat biomarkers in their blood had a 44% lower risk of diabetes compared to those with the lowest levels of dairy fat. This suggests that dairy products, particularly full-fat dairy products, may play a protective role against diabetes. One of the reasons for this may be that fat provides satiety, a sense of feeling full. When people cut fat out of their diet, they often replace it with sugars and other quick-digesting carbohydrates, all of which can have detrimental effects on the hormones that regulate appetite, especially insulin, which can ultimately raise the risk for diabetes.

However, the study authors emphasized that more research is still needed.

What does current research say?

The evidence remains mixed. Some studies find no link between whole-fat dairy and higher body mass index (BMI), while others suggest whole-fat dairy may lower BMI. In one review of 16 studies, 11 found that high-fat dairy correlated to a lower BMI. The other five showed that full-fat dairy did not affect weight.

Some studies show that dairy, regardless of fat content, does not affect heart disease risk. Others show that dairy protects heart health, no matter the fat content. Current research suggests that dairy, whether it be low or high-fat, is not harmful to heart health. Researchers of one study found no difference in blood pressure or cholesterol between people who ate low-fat dairy, full-fat dairy, or no dairy at all.

However, there is more to dairy than just saturated fat. It appears that yogurt and cheese are more heart-protective than milk due to fermentation.

Studies on diabetes are similarly inconclusive. Some link full-fat dairy to reduced diabetes risk, while others suggest low-fat and full-fat dairy can help regulate blood sugar levels. In contrast, other studies show that only full-fat dairy is protective. However, some research indicates that increased dairy consumption might raise insulin levels in certain individuals.

In terms of fertility, one study showed that women who consumed high-fat dairy products had a lower risk of having irregular menstrual cycles. Other research points to the connection between a diet high in saturated fat intake and increased infertility. So, keeping tabs on your total saturated fat intake may be important if trying to conceive.

Bottom Line: There’s no one size fits all

Research continues to evolve, but full-fat dairy may have been unfairly vilified. Whole-fat dairy can promote satiety, aid nutrient absorption, and potentially lower disease risk. Meanwhile, low-fat dairy remains a lower-calorie option recommended by health authorities like the USDA.

Ultimately, it’s important to make the right choice for you and your body, keeping in mind your health goals, taste preferences, and how often you consume dairy.

Disclaimer: These statements in this blog post have not been evaluated by the Food and Drug Administration. The information provided here is for educational purposes only and should not be considered as medical advice. It's essential to consult with a qualified healthcare professional before making any dietary or lifestyle changes.

Resources:

Oteng AB, Kersten S. Mechanisms of Action of trans-Fatty Acids. Adv Nutr. 2020 May 1;11(3):697-708. doi: 10.1093/advances/nmz125. PMID: 31782488; PMCID: PMC7231579.

Tucker LA, Erickson A, LeCheminant JD, Bailey BW. Dairy consumption and insulin resistance: the role of body fat, physical activity, and energy intake. J Diabetes Res. 2015;2015:206959. doi: 10.1155/2015/206959. Epub 2015 Jan 29. PMID: 25710041; PMCID: PMC4325471.

American Heart Association. (n.d.). Saturated fats. Retrieved December 13, 2024, from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/saturated-fats

American Heart Association. (n.d.). Monounsaturated fats. Retrieved December 13, 2024, from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/monounsaturated-fats

Heileson JL. Dietary saturated fat and heart disease: a narrative review. Nutr Rev. 2020 Jun 1;78(6):474-485. doi: 10.1093/nutrit/nuz091. PMID: 31841151.

Pimpin L, Wu JH, Haskelberg H, Del Gobbo L, Mozaffarian D. Is Butter Back? A Systematic Review and Meta-Analysis of Butter Consumption and Risk of Cardiovascular Disease, Diabetes, and Total Mortality. PLoS One. 2016 Jun 29;11(6):e0158118. doi: 10.1371/journal.pone.0158118. PMID: 27355649; PMCID: PMC4927102. 

Schmidt KA, Cromer G, Burhans MS, Kuzma JN, Hagman DK, Fernando I, Murray M, Utzschneider KM, Holte S, Kraft J, Kratz M. Impact of low-fat and full-fat dairy foods on fasting lipid profile and blood pressure: exploratory endpoints of a randomized controlled trial. Am J Clin Nutr. 2021 Sep 1;114(3):882-892. doi: 10.1093/ajcn/nqab131. PMID: 34258627; PMCID: PMC8408839. 

Dairy consumption in association with weight change and risk of becoming overweight or obese in middle-aged and older women: a prospective cohort study, Rautiainen, Susanne et al. The American Journal of Clinical Nutrition, Volume 103, Issue 4, 979 – 988

Janiszewska J, Ostrowska J, Szostak-Węgierek D. Milk and Dairy Products and Their Impact on Carbohydrate Metabolism and Fertility-A Potential Role in the Diet of Women with Polycystic Ovary Syndrome. Nutrients. 2020 Nov 13;12(11):3491. doi: 10.3390/nu12113491. PMID: 33202986; PMCID: PMC7696580.

J.E. Chavarro, J.W. Rich-Edwards, B. Rosner, W.C. Willett, A prospective study of dairy foods intake and anovulatory infertility, Human Reproduction, Volume 22, Issue 5, 1 May 2007, Pages 1340–1347, https://doi.org/10.1093/humrep/dem019

Guillermo Mena-Sánchez, Nerea Becerra-Tomás, Nancy Babio, Jordi Salas-Salvadó, Dairy Product Consumption in the Prevention of Metabolic Syndrome: A Systematic Review and Meta-Analysis of Prospective Cohort Studies, Advances in Nutrition, Volume 10, Supplement 2, 2019, Pages S144-S153, ISSN 2161-8313, https://doi.org/10.1093/advances/nmy083.

Shin S, Lee HW, Kim CE, Lim J, Lee JK, Kang D. Association between Milk Consumption and Metabolic Syndrome among Korean Adults: Results from the Health Examinees Study. Nutrients. 2017 Oct 8;9(10):1102. doi: 10.3390/nu9101102. PMID: 28991181; PMCID: PMC5691718.

Lee M, Lee H, Kim J. Dairy food consumption is associated with a lower risk of the metabolic syndrome and its components: a systematic review and meta-analysis. Br J Nutr. 2018 Aug;120(4):373-384. doi: 10.1017/S0007114518001460. Epub 2018 Jun 6. PMID: 29871703.

Kratz M, Baars T, Guyenet S. The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease. Eur J Nutr. 2013 Feb;52(1):1-24. doi: 10.1007/s00394-012-0418-1. Epub 2012 Jul 19. PMID: 22810464.

Fontecha, J., Calvo, M. V., Juarez, M., Gil, A., & Martínez-Vizcaíno, V. (n.d.). Milk and dairy product consumption and cardiovascular diseases: An overview of systematic reviews and meta-analyses. Advances in Nutrition. https://doi.org/10.1093/advances/nmy099

Schmidt KA, Cromer G, Burhans MS, Kuzma JN, Hagman DK, Fernando I, Murray M, Utzschneider KM, Holte S, Kraft J, Kratz M. Impact of low-fat and full-fat dairy foods on fasting lipid profile and blood pressure: exploratory endpoints of a randomized controlled trial. Am J Clin Nutr. 2021 Sep 1;114(3):882-892. doi: 10.1093/ajcn/nqab131. PMID: 34258627; PMCID: PMC8408839