Is Skim Milk Less Constipating Than Whole Milk?

January 6, 2026 •

4 min read

According to research published in the journal Nutrition, scientists found that fat-free milk supplementation led to increased regularity and softer stools in patients with chronic constipation. While milk fat is often cited as a potential contributor to constipation, this research suggests skim milk might have a different, less constipating effect than whole milk.

Quick Summary

This article examines the digestive differences between skim milk and whole milk, focusing on how fat content and lactose may influence constipation. It explores why some people experience constipation with dairy, while others do not, and provides practical advice for managing milk-related digestive issues.

Key Points

Skim Milk Advantage: Studies indicate that skim or fat-free milk may increase intestinal motility and improve stool softness, making it less constipating than whole milk for some people.
Whole Milk Slows Digestion: The high fat content in whole milk can slow down the digestive process, potentially leading to constipation, especially when consumed in large quantities.
Lactose Intolerance Factor: Both skim and whole milk contain lactose. For individuals with lactose intolerance, either milk type can cause constipation, bloating, or diarrhea, so the fat content is not the main issue.
Nutrient Absorption Trade-offs: Whole milk aids in the absorption of fat-soluble vitamins (A, D), while skim milk lacks the necessary fat for this process.
Probiotics Can Help: Fermented dairy products like yogurt and kefir, which are often lower in lactose, contain probiotics that can aid gut health and relieve constipation.
Individual Sensitivity is Key: The right choice depends on whether your digestive issues stem from fat sensitivity, lactose intolerance, or other dietary factors, such as low fiber intake.

Understanding the Link Between Dairy and Constipation

For many, dairy is a beloved part of their diet, but for others, it can cause digestive upset, including constipation. The relationship is complex and depends on individual sensitivities to either the milk fat, the protein, or the milk sugar, lactose.

The Role of Milk Fat in Digestion

Whole milk contains a higher concentration of fat compared to skim milk. The high-fat content of whole milk and other full-fat dairy products can slow down the digestive process. This delayed transit time can lead to a harder, drier stool as the colon absorbs more water from the waste. Studies have suggested that excessive consumption of milk leads to constipation because unabsorbed fatty acids can bind to calcium in the intestines, forming insoluble 'soaps' that can cause blockages. Skim milk, being nearly fat-free, does not present this same issue, which is a key reason it is often considered less constipating.

The Impact of Lactose on the Gut

Both whole and skim milk contain lactose, a sugar that requires the enzyme lactase for proper digestion. People with lactose intolerance lack sufficient lactase, meaning undigested lactose travels to the large intestine where it is fermented by gut bacteria. While this process most commonly causes symptoms like bloating, gas, and diarrhea, in a subset of people (around 30% according to one review), it can lead to constipation instead. This is thought to be due to the methane gas produced during fermentation, which can slow intestinal motility. If your constipation is caused by lactose intolerance, the fat content of the milk is irrelevant—both whole and skim milk will have a similar effect on you. Lactose-free milk or dairy alternatives would be better choices.

Scientific Studies on Skim Milk and Constipation

A specific study from Turkish scientists, published in Nutrition, investigated the effect of fat-free milk on chronic constipation. The research involved patients with chronic constipation and a control group of healthy individuals. They were given fat-free milk, followed later by whole milk. The results showed that fat-free milk supplementation increased regularity and improved stool softness in the chronic constipation patients. The researchers found that fat-free milk increased the levels of certain hormones, like motilin, which stimulate intestinal mobility. Whole milk, conversely, caused a decrease in these hormone levels in the control group. These findings provide compelling evidence that, for some, the lower fat content of skim milk can be beneficial for digestive regularity.

Comparison Table: Skim Milk vs. Whole Milk for Digestion


Feature	Skim Milk (Fat-Free)	Whole Milk (Full-Fat)
Fat Content	Very low (under 0.5%)	High (around 3.25%)
Digestive Speed	Generally faster; less likely to slow motility.	Slower; high fat content can delay transit time.
Potential for Constipation (Fat-Related)	Low; lacks the fatty acids that can form blockages.	Higher; unabsorbed fats can bind with calcium to form soaps, causing constipation.
Lactose Content	Same as whole milk; can cause issues for those with lactose intolerance.	Same as skim milk; can cause issues for those with lactose intolerance.
Hormonal Impact	May increase hormones like motilin that stimulate intestinal motility.	May decrease hormones that stimulate intestinal motility in some individuals.
Nutrient Absorption	Fat-soluble vitamins (A, D) are not absorbed as effectively without fat.	Fat aids in the absorption of fat-soluble vitamins (A, D).

Practical Tips for Dairy and Digestive Health

If you suspect dairy is causing your constipation, consider your individual situation. Not everyone is affected the same way. If you are not lactose intolerant, the issue may be the fat content. If you are lactose intolerant, reducing all forms of dairy or switching to lactose-free versions is the best strategy. Here are some actionable steps:

Gradual Transition: If you are used to whole milk, consider a gradual switch. Move from whole to 2%, then 1%, and finally to skim milk to let your body adjust.
Moderate Consumption: Try consuming smaller quantities of milk to see if that helps manage symptoms.
Consider Lactose-Free: For lactose intolerance, lactose-free milk provides the same nutrients without the digestive distress caused by lactose.
Explore Fermented Dairy: Yogurt and kefir contain beneficial probiotics that can improve overall gut health and may decrease the likelihood of constipation.
Maintain Hydration: Regardless of milk choice, ensure adequate fluid intake. Dehydration is a common cause of constipation.
Focus on Fiber: Increase your fiber intake from fruits, vegetables, and whole grains. Fiber adds bulk to stool and promotes regular bowel movements, counteracting any potential constipating effects of other foods.

Conclusion

For individuals with a sensitivity to dairy fat, skim milk is less constipating than whole milk. The higher fat content in whole milk can slow down intestinal transit, while research suggests fat-free milk may actually promote regularity by influencing gut hormones. However, the primary trigger for dairy-related digestive issues is often lactose intolerance, in which case the fat content is irrelevant and both skim and whole milk can cause problems. The key is to identify your specific sensitivity and adjust your dairy consumption or type accordingly. For those who tolerate dairy well, neither whole nor skim milk is inherently constipating, and factors like overall diet, hydration, and fiber intake play a much larger role in promoting digestive health.

This article is for informational purposes only and does not constitute medical advice. For personalized dietary advice, consult a healthcare professional.

Frequently Asked Questions

Yes, milk can cause constipation in some adults. This can be due to a sensitivity to the milk's fat content, as seen with whole milk, or it can be a symptom of lactose intolerance, where the milk sugar causes digestive issues.

For some, the high fat content of whole milk is the main reason for constipation. The fat can slow down intestinal transit and, when combined with calcium, form soaps that can cause blockages. However, for others, lactose intolerance is the real culprit.

The cause varies. Some people react to the fat content, while many others, particularly those with lactose intolerance, experience constipation due to the maldigestion of milk sugar. Cow's milk protein allergy can also be a cause, especially in children.

Yes. If your constipation is caused by lactose intolerance, both skim and whole milk will likely cause the same problem, as both contain similar amounts of lactose. In this case, switching to lactose-free dairy or an alternative milk is the best approach.

For those sensitive to dairy, plant-based milks like almond, oat, or rice milk can be good alternatives. Fermented dairy products like yogurt and kefir, which are easier to digest due to their probiotic content, are also often well-tolerated.

If your constipation resolves after eliminating dairy products from your diet for a few weeks and then returns when you reintroduce them, it's a strong indication that milk is the cause. You can also try eliminating just whole milk first to see if fat is the issue.

No. For some, only high-fat or high-lactose products cause issues. Fermented products like yogurt and kefir, which contain probiotics and are easier to digest, often do not cause constipation and can even help.

Common dietary causes of constipation include a diet low in fiber, dehydration, and excessive intake of processed foods, refined grains, and red meat.