- A new study suggests that a 2-day oatmeal diet can help lower “bad” LDL cholesterol levels, promote weight management, and improve blood pressure.
- The findings suggest that eating a higher amount of oats for two days may be more effective than eating small amounts over a longer period of time.
- Some experts say fiber may be replacing protein as the “it” nutrient as people begin to focus more on gut health.
Oats and oatmeal are often linked to various health benefits. These might include lower cholesterol and helping with weight management.
A new study published in
Metabolic syndrome is a group of conditions. Together, these conditions can raise your risk for coronary heart disease, stroke, and diabetes.
“This is an interesting, well-controlled study, but it needs to be interpreted carefully,” said Michelle Routhenstein, a preventive cardiology dietitian at EntirelyNourished.com, who was not involved in the study.
“When intake is tightly managed with lower calories, minimal saturated fat, high fiber, and limited dietary variability, it is easier to observe rapid drops in LDL cholesterol. This does not mean oats only work in very large amounts or over just two days. It mainly reflects how powerful dietary control can be in a research setting,” Routhenstein told Healthline
This small study analyzed two randomized controlled intervention studies that ran in parallel, with 34 participants in each. One group was assigned as the oat group, and the other was a control group.
Those in the oat group were asked to consume three oat meals a day for two days instead of their typical diet. Each meal consisted of 100 grams of rolled oat flakes boiled in water.
In order to ascertain the long-term effects, the two-day period was followed by a six-week follow-up period where the participants returned to their typical diet without oats.
The control group consumed standardized control meals without oats on each intervention day. These meals did not consist of their typical diet, but were macronutrient-adapted to the oat group.
The study that ran parallel to this one was the six-week intervention. During this longer intervention, the oat group replaced one meal per day with an oatmeal containing 80 grams of rolled oat flakes, while maintaining their typical diet. The control group maintained their typical diet while remaining abstinent from oats for the six weeks.
All participants had abdominal obesity. They also had at least two further metabolic syndrome traits, including high blood pressure, impaired glucose metabolism (prediabetes), and dyslipidemia.
The short-term oat group saw around a 10% reduction in LDL cholesterol levels. They also lost an average of around four pounds and saw slightly lower blood pressure levels.
“I think the methodology of this study warranted a more aggressive approach to consuming the same thing (in this case, oats) for two full days and this approach may not be as realistic in real life,” said Kristin Kirkpatrick, a dietitian at the Cleveland Clinic Department of Wellness & Preventive Medicine and a senior fellow at the Meadows Behavioral Healthcare in Wickenburg, AZ. Kirkpatrick wasn’t involved in the study.
“People crave variety, and the body requires that we consume varying vitamins, minerals, antioxidants, etc.,” she told Healthline.
Routhenstein explained that in general, cholesterol changes happen more gradually. “People eat a wider mix of foods, adherence varies, weight may change, and metabolic responses differ over time,” she said.
She explained that these studies are useful for understanding biological mechanisms, such as how beta-glucan affects cholesterol absorption, but they do not replace the value of consistent, long-term habits.
The effects of the oat-based diet were still seen six weeks later.
“A short-term oat-based diet at regular intervals could be a well-tolerated way to keep the cholesterol level within the normal range and prevent diabetes,” study author Marie-Christine Simon, PhD, a registered dietitian and junior professor at the Institute of Nutritional and Food Science at the University of Bonn, said in a press release.
The effects of the oatmeal diet were seen in higher levels in the two-day intervention than they were in the six-week intervention.
The longer intervention, where individuals consumed 80 grams of oatmeal per day without any other restrictions, still showed small positive effects, however.
“Oats have been found to be a powerful addition to a heart-healthy diet, and I often recommend oats to my patients who are seeking a dietary approach to lowering lipids and managing blood sugar,” noted Kirkpatrick.
While oatmeal can be a healthy option to help lower your cholesterol, there are other proven strategies.
“I recommend focusing on sustainable, long-term dietary habits rather than short-term diets. Because heart disease develops gradually, daily eating patterns matter most,” Routhenstein said.
Kirkpatrick added that your diet should consist of “an abundance” of plants and healthy fats.
She said that a balanced diet should be low in added sugar and focus on plant-based proteins when possible. Incorporating fatty wild fish, skinless white meat poultry, and small amounts of lean cuts of meat is also advised.
“Diet plays a powerful role, but it’s not the only star factor. Getting adequate physical activity, managing stress, having a healthy sleep routine, limiting alcohol, and stopping smoking all will play an important role,” said Kirkpatrick.
The recent trend of “fibermaxxing” has some people stating that fiber is the new “it” nutrient, replacing protein.
“There is a consumer need in terms of digestion and gut health, and that’s something we’ve seen the last few years,” Sherry Frey, health and wellness expert at NIQ, said in a press release.
“The younger generation understands that digestive health is linked to better skin and improved cognitive function,” she continued.
While fiber is becoming more popular, Routhenstein cautioned that fiber shouldn’t replace protein. Evidence supports dietary patterns that include both adequate protein and high fiber to support muscle, metabolic, and heart health.
“Fiber and protein serve distinct physiological roles. Higher fiber intake is consistently associated with lower cardiovascular disease risk, improved blood sugar control, better gut health, and reduced all-cause mortality, yet most adults consume far less fiber than recommended,” Routhenstein said.