This article about milk and weight loss would be very relevant to you if you have been on the Glycemic Index and ‘low-carb” bandwagon. Milk has been touted as a super-food with many benefits for those losing weight. We have summarized essential scientific information about milk and weight loss to allow you to make an informed decisions.
There has been lot of debate in recent years about milk and weight loss. Most content about milk and weight loss on the internet promotes milk as beneficial for weight loss. Some population studies have shown that drinking milk actually helps in losing weight. One needs to keep in mind that a lot of population studies have been funded by the dairy industry and have vested interests.
The goal of this article is to approach this subject purely from a scientific point of view. Irrespective of what the population studies are showing, we want to review scientific literature to assess what happens in your body when you consume milk .
Table of Contents for Article
- 1 Milk and Weight Loss – An Overview
- 2 What About Saturated Fat in Milk
- 3 Insulin and Its Role in Weight Gain
- 4 Glycemic Index and Insulin Index
- 5 Low GI Food That Spike Insulin Levels
- 6 Milk and Weight Loss – Essential Terminology
- 7 Glycemic Index of Milk
- 8 How Milk Affects Insulin Levels
- 9 Milk and Insulin Resistance
- 10 Milk Crashes Blood Sugar Levels
- 11 Glycemic Index and Insulin Index Relationship for Milk
- 12 Does Fat Content in Milk Affect Insulin Response
- 13 What about calcium from milk
- 14 Summary of How Milk Could Cause Weight Gain
- 15 Saturated Fat Double Whammy
- 16 Milk and Weight Loss – The Verdict
Milk and Weight Loss – An Overview
Milk is the white liquid that is produced in the mammary gland of mammals. Milk is food for infants of mammals. Infants get all their nutritional needs from milk. Unlike other mammals, humans continue to consume milk beyond infancy.
Humans of all ages consume considerable amounts of milk even though a large part of the population is lactose intolerant. Find out more about milk and its composition. You would also find the following diagram of milk products useful.
What About Saturated Fat in Milk
The common thinking is that any weight gain resulting from drinking milk is probably caused by saturated fat. It is for this reason that people opt for low-fat or skim milk. While it could be a contributor to weight gain, the effect of saturated fat may not be as pronounced.
This is because milk’s effect on your insulin levels probably has a bigger impact on your waistline than milk’s saturated fat content.
Insulin and Its Role in Weight Gain
Before looking at milk and weight loss, a quick overview of Insulin and its effects are necessary.
Insulin is a hormone secreted by your pancreas and is essential for carbohydrate and fat metabolism in your body. Insulin causes cells in the liver, skeletal muscles, and fat tissue to absorb glucose from the blood. Important for those trying to lose weight to understand is that insulin can also force excess glucose to be converted into fat and stored in your fat cells.
Insulin is a potent fat storage hormone. In the presence of higher levels of insulin, the body prefers to store fat and not to burn it. This is a significant fact for someone wanting to lose weight. When insulin levels are raised, you would be storing fat even though you are on a calorie restricted diet. Your cells could be starving for energy and yet all the calories that you are consuming are being stored in your fat cells in the presence of higher levels of insulin.
Insulin Resistance is a condition where the body loses sensitivity to the effects of the Insulin hormone. The body needs increasing amount of insulin to manage blood glucose levels as it becomes more Insulin Resistant. You become increasingly susceptible to gaining weight or find it very difficult to lose weight, with increasing levels of Insulin Resistance.
Glycemic Index and Insulin Index
Certain foods when eaten, cause your blood glucose to spike. Your body needs to respond correspondingly with a spiked release of insulin to quickly bring blood glucose levels back to within the required safe band.
Foods that spike glucose levels usually have a very high Glycemic Index. The Glycemic Index (GI) is an estimate of how fast blood glucose levels rise after a particular food is eaten, when compared to consumption of pure glucose. Glucose has a Glycemic Index of 100. It is mostly the case that any food which causes a spike in blood sugar will also result in a spiked response in Insulin levels.
The Glycemic Index is very popular in the weight loss industry. People trying to lose weight use this as an indicator of “good carbs” or “bad carbs”. The GI is an indicator of foods that spike blood sugar and thus cause Insulin Resistance.
Low GI Food That Spike Insulin Levels
Unfortunately, there are certain foods that do not spike glucose levels but spike insulin levels instead. It is for this reason that the Insulin Index could be a more useful tool to identify Insulin Resistance causing food.
The Insulin Index (II) is a measure of the insulin response to various types of foods. The Glycemic Index relies on monitoring of blood glucose levels. The Insulin Index however, monitors the levels of the blood insulin levels after a meal.
Milk and Weight Loss – Essential Terminology
In order to better understand this article, there are some key terms you should know. The Merriam Webster online dictionary defines the following key terms;
Insulinogenic; of, relating to, or stimulating the production of insulin
Insulinotropic; stimulating or affecting the production and activity of insulin
Hypernsulinemia; the presence of excess insulin in the blood
Glycemic Index of Milk
Milk generally has a very low Glycemic Index. Milk and dairy products typically have a Glycemic Index of less than 50. This falls within the range of highly healthy foods if the Glycemic Index is used as an indicator.
Glycemic Index of dairy products sourced from Harvard Health Publications.
Apple has a Glycemic Load of 6 while full fat milk has a Glycemic Load of only 5. This means that full fat milk has a lower impact on your blood sugar than an apple. This is based on the assumption that the Glycemic Index (GI) of these foods is correlated with their respective Insulin Indexes. Based on this reasoning, you could drink skim milk and eat dairy products the whole day without disrupting your blood sugar levels. Is this really the case?
How Milk Affects Insulin Levels
A study was published in the Journal Diabetologica in 1986. The authors of this study sampled blood glucose and insulin levels in subjects with untreated Type 2 diabetes. The samples were taken after these patients had consumed foods containing either sucrose, glucose, fructose or lactose. All food portions contained 50g of carbohydrates.
Milk turned out to be a potent trigger for the secretion of insulin. The insulin response was almost 5 times greater than would be anticipated from its glucose response. The authors suggested that the body’s insulin response (i.e. the rise in blood insulin levels after meal consumption) to milk could not be correlated to its Glycemic Index. They also concluded that milk was a potent insulin secreter in type 2 diabetic patients.
A study was published in the Klin Wochenschr Journal in 1991. The authors reported that the post-meal glucose and insulin responses to a milk containing breakfast did not correlate in healthy people. Milk had a much higher insulin response than would be expected from its low Glycemic Index.
A study was published in the European Journal of Clinical Nutrition in 2001. The investigators found that the addition of even an ordinary amount (200 ml) of milk to a meal caused a spiked insulin response. The authors further said that the Glycemic Index of milk is low but it seemed to have the insulin response of very high Glycemic Index white bread. Even the addition of milk to low Glycemic Index mixed meals brought about an elevated insulin response.
A study was published in the American Journal of Clinical Nutrition in 2001. The investigators looked at regular and fermented milk products. They found a discrepancy between Glycemic Index and the Insulin Index of milk. Despite very low Glycemic Index (GI = 15-30), high Insulin Index was found (II = 90-98) for both milk and yoghurt.
This showed again that milk induced a potent insulin response. From this study , it was concluded that milk’s insulinotropic effect was not related only to the carbohydrate component of milk, but also to some yet unidentified food component.
Milk and Insulin Resistance
An article was published in the European Journal of Clinical Nutrition in 2005. In this study, 24 boys aged 8 were asked to consume 53 grams of protein either in the form of milk or meat. The investigators measured insulin and glucose levels after 7 days. They also assessed the level of Insulin Resistance if any had been induced.
The researchers found that fasting insulin levels doubled in the milk group. Insulin resistance in this group increased similarly.
There was no increase in insulin levels or any induced insulin resistance in the meat-eating group. The researchers concluded; “Our results show that a short-term high milk, but not meat, intake increased insulin secretion and resistance. The long-term consequences of this are unknown.”
Milk Crashes Blood Sugar Levels
A study was published in the British Journal of Medicine in 2005. This study confirms the observation that consumption of milk induces a reactive hypoglycemia. Hypoglycemia is a condition that occurs when blood sugar drops too low. 4 of the 9 participants’ blood glucose concentrations had dropped below baseline within 60 min after consuming milk. The Insulin spike overcompensated and forces more glucose into your cells than necessary. This also explains the extreme thirst experienced after drinking milk or a milky beverage.
Glycemic Index and Insulin Index Relationship for Milk
A study was published in the British Journal of Nutrition in 2000. The authors stated that for most foods, there is a strong correlation between the Glycemic Index and Insulin Index. One exception to this correlation are milk and dairy products. Milk and dairy products typically have a low Glycemic Index but a very high Insulin Index.
The authors of this study further stated, “This inconsistent behaviors of milk products has not been acknowledged, and potential metabolic consequences remain to be elucidated”. It appears that milk products seem to be an exception to the linear GI-II correlation rule, in that the II cannot be predicted from the GI.
Does Fat Content in Milk Affect Insulin Response
A study assessing Glycemic Index and Insulin Index levels of milk and fermented milk was published in the American Journal of Nutrition in 2001. The Glycemic Index and Insulin Index from this study was as follows;
- Regular milk (3%fat) GI=30 II=90
- Fermented milk : Filmjolk by Skånemejerier GI=15 II=98
- Fermented milk : Ropy milk by Arla GI=15 II=97
This study goes to show that both fermented and regular milk have a high Insulin Index.
A study assessing the Glycemic Index and the Insulin Index of whole and skim milk was published in the British Journal of Nutrition in 2004. The Glycemic Index and Insulin Index from this study was as follows;
- Whole milk : GI=42 II=148
- Skim milk : GI=37 II=140
There did not seem to be significant difference in the Insulin Index of either whole or skim milk. Another study published in the American Journal of Clinical Nutrition in 2005 also showed high Insulin Index for reconstituted skim milk (0.1% fat).
A study was published in the British Journal of Nutrition in 2005. The authors of that study investigated the insulin response of skim milk and whole milk. The authors concluded that the dissociation of the Glycemic Index and Insulin Index in milk is not related to its fat content.
A study published in the American Journal of Clinical Nutrition in 1997 further showed that the Insulin Index of cheese was actually 45. This was the only dairy product with an Insulin Index that correlated with its GI.
What about calcium from milk
This subject requires an in-depth analysis of the available research. For the purpose of this article, a meta-study was referred. This is a study that was published in the Journal of Nutrition in 2008. This study evaluated 49 previous studies that assessed the effect of dairy products or calcium intake on body weight.
Of the 49 randomized trials assessing the effect of dairy products or calcium supplementation on body weight, 41 showed no effect, two demonstrated weight gain, one showed a lower rate of gain, and five showed weight loss. The authors concluded that the majority of the current evidence from clinical trials does not support the hypothesis that calcium or dairy consumption aids in weight or fat loss.
Summary of How Milk Could Cause Weight Gain
For many carbohydrate-rich foods there is a linear correlation between the GI and the Insulin Index. (Reference : British Journal of Nutrition)
This is certainly not the case for milk and almost all dairy products. Milk possesses insulinogenic properties that is not related to its carbohydrate content. (Reference : European Journal of Clinical Nutrition)
The insulinogenic properties of milk are conclusive by virtue of the abundant scientific research available to support it. Milk consumption can cause hypernsulinemia. In a short time, hyperinsulinemia could result in Insulin Resistance.
Milk consumption can cause insulin resistance in the short-term, even though there is no elevation in blood sugar levels. Recapping the study published in the European Journal of Clinical Nutrition in 2005, fasting insulin levels doubled after 7 days of milk consumption.
This is probably the confusing part about milk for many. Most people use the Glycemic Index as a guide to identify foods that will cause insulin resistance. Milk being a low Glycemic Index food and has remained under the radar.
Except for cheese with an Insulin Index score of 45 all dairy products (whole milk, skimmed milk, yoghurt, ice cream, cottage cheese and fermented milk products) have been shown to have potent insulinogenic properties.
Saturated Fat Double Whammy
Milky beverages such as lattes can be harmful to your weight loss efforts. The hyperinsulinemia arising from drinking such a beverage causes most of all calories consumed with it to be stored as fat.
Milk and Weight Loss – The Verdict
The authors of a JAMA study suggested that the insulin response from drinking milk is similar to consuming a high Glycemic Load carbohydrate. High Glycemic Load carbohydrates have been implicated as an underlying cause of Insulin Resistance.
Epidemiological studies on the effect of milk on weight loss have had conflicting outcomes. It is baffling how population studies can find milk to be helpful in weight loss when it is one of the most potent inducer of insulin secretion.
Our advice to readers would be the same as what researchers are advising based on the findings of the above studies. On researcher suggested, “Until well-controlled interventions can corroborate epidemiological associations, our data suggest caution is warranted in recommending higher milk consumption for adults, particularly those at risk for diseases of insulin resistance.”
Milk’s insulin spiking properties are well proven. What is also proven without a doubt is that chronic insulin spikes cause insulin resistance. Insulin resistance makes you susceptible to weight gain. If you are trying to lose weight, it becomes more difficult when you have insulin resistance.
Consume milk products very sparingly until you have successfully achieved your weight loss goals. This would be the best advice for now with regards to milk and weight loss.