Three Dairy Servings a Day for 12 Weeks: What the Trial Shows and Where It Stops

The short answer: In a 12-week trial of 74 adults with overweight or obesity, the groups eating three dairy servings a day showed no adverse cholesterol or lipid levels. Their weight stayed stable and their glucose and HbA1c were unchanged. Blood pressure did not get worse, and systolic pressure fell in one dairy group. Triglycerides rose briefly at week 4 and were back to baseline by week 12. The trial can't tell you whether full-fat dairy changes your long-term risk of heart disease or diabetes. The researchers call it small and short, and participants were metabolically healthy at baseline, so the results may not apply to people with high LDL. If your LDL is high or you take a statin, talk to your doctor before you change what you eat.

The low-fat advice, and the single link behind it

The case for low-fat dairy rests on one well-supported connection. As Harvard Health puts it, too much saturated fat in the diet can raise LDL, the "bad" cholesterol. In plain terms, LDL is the particle that carries cholesterol around the body, and doctors watch it because higher levels over many years are thought to feed buildup in artery walls. Full-fat dairy contains more saturated fat, so cutting back on it became a simple way to aim for lower LDL.

Harvard Health's summary of the research is more mixed than that single link suggests. Across studies, dairy neither raised nor lowered cardiovascular risk overall. Its practical advice is still careful: full-fat dairy in moderation can fit a healthy diet, but because it contains more calories and saturated fat, it's best to limit it to one serving a day. That page comes from one health publisher and isn't an official dietary guideline. It's still a useful benchmark when the trial below tested three servings a day.

A timeline of the evidence

The research and the news coverage came at different times:

• 2015: A meta-analysis pooled trials that compared cheese with butter. With an average cheese intake of about 145 g a day, cheese lowered LDL by 6.5% compared with butter (0.22 mmol/l lower; 95% CI 0.14 to 0.29 mmol/l lower).
• January 2026: News-Medical reported the weight and blood marker results of a 12-week, 74-person dairy trial.
• November 2026: A ScienceDaily release covered the paper in The Journal of Nutrition, including lead researcher Gerald Harvey Anderson's comments on blood pressure.

The 2015 result is easy to over-read. It shows that cheese differs from other sources of saturated fat, at least when compared with butter. It doesn't show that cheese lowers cholesterol compared with eating no butter or cheese at all, and the meta-analysis summary doesn't say why the two differ.

Inside the trial: three diets for 12 weeks

The trial was published in The Journal of Nutrition in 2026 and led by Anderson, of the University of Toronto, ScienceDaily reports. Dairy-sector programs paid for it (Dairy Research Cluster 3, under the Canadian Agricultural Partnership AgriScience Program), along with Mitacs Accelerate. In my view, industry funding doesn't make the results wrong, but it's a fair reason to wait for independent trials before treating them as settled.

According to News-Medical, 74 adults aged 25 to 60 with overweight or obesity were randomly assigned to one of three diets:

1. Low dairy, calorie-restricted: little dairy, with a target deficit of 500 kcal a day.
2. Three dairy servings, energy-neutral: three daily servings within an energy-neutral diet.
3. Three dairy servings, no calorie limit: three daily servings, without specific calorie restrictions.

News-Medical describes both dairy arms as full-fat. The ScienceDaily release says only "dairy". Neither report describes a low-fat dairy arm, and the low-dairy group was also cutting calories. So the trial doesn't appear to test the swap many readers are thinking about, such as full-fat yogurt in place of low-fat. What it tests is whether three dairy servings a day caused harm compared with a calorie-restricted, low-dairy diet. Neither report gives the size of a serving in grams.

Results, measure by measure

Read the weight row carefully. The dairy groups held steady while the restricted group lost a little, but the groups also had different calorie targets. The trial can't separate what dairy did to weight from what the calorie targets did.

The reports we found cover glucose and HbA1c. They don't report insulin resistance. They also don't break the results down by milk, yogurt and cheese, so they can't tell you which food was behind which result.

Blood pressure fell, but not only with dairy

Anderson described improvements in blood pressure among participants who ate more dairy. News-Medical's report adds an important detail. Systolic pressure fell in the no-limit dairy group, and it also fell in the group that ate little dairy and cut calories. When the comparison group improves as well, it's harder to argue that dairy alone lowered blood pressure.

Our 5 November piece on potassium and salt looked at a different food-based approach to blood pressure. It also explained who needs a doctor's check before adding potassium. The same applies here: if you take blood pressure medication, check any change to your diet with your doctor.

Limits the researchers name themselves

Some coverage treats this trial as proof that full-fat dairy is good for the heart. That claim is bigger than the data. The researchers say so themselves: the study was relatively small, lasted only three months and did not establish long-term effects on diabetes or heart disease. The reported limitations go further:

• Fewer people enrolled than planned.
• It wasn't powered to detect long-term cardiometabolic outcomes, such as heart attacks, strokes or new cases of diabetes.
• Participants were metabolically healthy at baseline, so the results may not apply to people with high LDL.

Three months of blood tests is a different kind of evidence from a long trial that counts heart events. A trial that could answer the question would be larger and longer, funded independently of the dairy industry, and would include people who already have high LDL. It would also compare three servings of full-fat dairy with three servings of low-fat dairy, with calories matched.

Myth versus evidence

• Myth: Full-fat dairy is now proven safe for your heart. Evidence: 74 adults were followed for 12 weeks, the trial looked at weight and blood markers, and no heart events were counted.
• Myth: Dairy lowers blood pressure. Evidence: Systolic pressure fell in a dairy group and also in the calorie-restricted, low-dairy group.
• Myth: Cheese lowers cholesterol. Evidence: In 2015, cheese lowered LDL compared with butter. It wasn't compared with eating no butter or cheese.
• Myth: The trial shows full-fat beats low-fat. Evidence: The published summaries don't describe a low-fat dairy arm.

Before you change anything: questions for your doctor

This is general information, not advice for your own situation. A doctor or registered dietitian can weigh your blood results and medications. These questions may help that conversation:

• If your LDL is high or you take a statin: Does the saturated fat in full-fat dairy matter for my LDL target, and how many servings fit? Saturated fat can raise LDL, and this trial's participants were metabolically healthy at baseline.
• If you have prediabetes or diabetes: Do glucose and HbA1c results from metabolically healthy adults tell us anything about me?
• If you're working on your weight: How do dairy calories fit my plan? The trial can't answer this, because its groups had different calorie targets.
• If your cholesterol is normal: Is it worth switching at all? The trial didn't compare full-fat with low-fat dairy, so it can't say whether the swap changes your numbers.

Quick questions

Is this trial new?

The paper appeared in The Journal of Nutrition in 2026. News-Medical covered the results in January 2026 and the ScienceDaily release followed in November, so the findings have been public for most of the year.

How many full-fat servings a day is reasonable?

This evidence doesn't give a number. Harvard Health suggests one full-fat serving a day, and the trial tested three in metabolically healthy adults. If you have high LDL or take cholesterol medication, agree on a number with your doctor.