Most experts recommend lower-fat milk, despite growing evidence for whole milk
Over the past 40 years, milk consumption among children has declined. Currently, 41% of U.S. children and adolescents are overweight or obese, according to U.S.

dietary guidelines from 2020-2025.
U.S. NHANES data in 2017-2018 shows that men between the ages of 2 and 19 consume about two cups equivalents of dairy per day, which is significantly less than the recommended equivalent of 2.5 to 3 cups (depending on age). In women, dairy consumption for girls 2 to 11 years is less than two cups, and for teen girls, is reduced to 1.3 cup equivalents. Low dairy consumption can affect weight health as well as nutrient adequacy and bone health.

Whole milk and healthy weight

Despite the growing evidence of a negative association between the consumption of whole-fat milk and obesity, many specialists still recommend fat-free and low-fat milk for children.
In a study published in the American Journal of Clinical Nutrition’s in 2022, “Association of Cow's Milk Intake in Early Childhood with Adiposity and Cardiometabolic Risk in Early Adolescence”, experts showed that consumption of higher-fat cow’s milk in early childhood was not linked to increased adiposity or adverse cardiometabolic health later in life. Moreover, findings did not support current recommendations to consume lower-fat milk to decrease the risk of later obesity.
In another study conducted in 2021 in the International Journal of Obesity, “Cow's Milk Fat and Child Adiposity: A Prospective Cohort Study,” researchers found that consuming reduced fat instead of full-fat cow's milk during childhood may not be effective in preventing overweight or obesity. There is also evidence that children who consumed whole milk had a 16% lower chance of being obese compared to the children who consumed lower-fat milk (0.1 to 2%).

Sugar content

Unlike fat content, the sugar content of milk may have a major effect on weight. A 2022 article from Nutrients, “The Relationship between Fluid Milk, Water, and 100% Juice and Health Outcomes among Children and Adolescents,” showed that milk consumption was not related to abdominal obesity and skinfold thickness (SFT). The study also showed the direct relationship between milk intake and bone strength. However, waist circumference and the BMI of flavored milk drinkers were significantly higher than that of those who did not consume milk, indicating the undesirable relationship between flavored milk and BMI.
Many flavored milks contain up to 12 grams of added sugar per 8-ounce serving, and it is recommended for children ages 2 years and older to limit added sugars to less than 10% calories per day.
Another 2020 USDA study, “Beverage Consumption and Growth, Size, Body Composition, and Risk of Overweight and Obesity: A Systematic Review,” concluded that there is no sufficient evidence about the relationship between milk type (i.e., milk fat content and flavor) and obesity in children.

A sufficient supply of nutrients

As some people have switched to plant-based milk alternatives, their children may also be served these types of milk. However, plant/non-dairy milk is not recommended as a replacement for regular milk.
Evidence showed that except for fortified soy milk, many plant-based/non-dairy milk alternatives lack the key nutrients found in cow's milk. According to HealthyDrinksHealthyKids.org, even when extra nutrients are added to plant-based/non-dairy milk alternatives, our bodies may not absorb those nutrients as well as they can from regular milk.
Potassium, calcium, and vitamin D are important dietary components of the public health diet for the general US population. While values may vary slightly, most dairy products are an excellent source of calcium and vitamin D and a good source of potassium. Reducing the consumption of fluid milk may leave room for sugary, high-calorie drinks that lack essential nutrients for children.
In the 2022 IFT FIRST conference, the importance of dairy products for children in other countries was emphasized. Mitch Kanter, chief scientific officer of the Rosemont-based Global Dairy Platform, in his presentation on "A World Without Cows," stated that "in countries like India, where over 60% of the population suffer from some form of protein-calorie malnutrition, and stunting is prevalent. Therefore, for low- and middle-income countries in the developing world, protein quality is extremely important.
As a result, for many children around the world, any form of dairy helps them maintain a healthy weight.
Reference:
https://www.dairyfoods.com/articles/95871-milk-consumption-supports-healthy-weight-in-children