From the Guidelines
Adipocytes (fat cells) generally stop increasing in number during late adolescence, typically around age 18-20, though they can continue to expand in size throughout life, and bones stop growing in length when growth plates (epiphyseal plates) close, which occurs at different times depending on the specific bone but generally completes between ages 18-25. The process of bone growth and development is closely linked to the intake of essential nutrients such as calcium, which is crucial for bone mineralization, a process that peaks at around 20 years of age 1. Some of the key factors that influence bone health include adequate nutrition, particularly calcium and vitamin D intake, as well as regular engagement in weight-bearing exercise, which has been shown to be strongly correlated with increased bone mineral density 1. Major long bone growth is typically finished by age 18 in females and age 20 in males, with the clavicle being the last bone to complete growth, often around age 25. This timing coincides with the end of puberty when sex hormones, particularly estrogen, signal growth plates to ossify and close. While new fat cells stop forming in most body areas after this period, the body maintains the ability to generate new adipocytes in response to extreme weight gain or in certain conditions. Understanding these developmental milestones helps explain why height increase becomes impossible after young adulthood and why weight management often becomes more challenging as we age, since existing fat cells can still enlarge even though new ones aren't typically being created. Key recommendations for promoting healthy bone development include ensuring adequate calcium and vitamin D intake, engaging in regular weight-bearing exercise, and maintaining a healthy weight, as excessive weight gain can lead to an increase in fat cell size, even if the number of fat cells remains relatively constant 1.
From the Research
Adipocytes (Fat Cells) Growth
- The increase in fat cells stops in adults, as the number of fat cells is constant over time when body weight is stable 2.
- However, an increase in body weight can cause an elevation of both fat cell size and number in adults 2.
- The bone marrow is an important source of renewal of fat cells during the entire life span, especially in obesity when ∼20% of all fat cells are derived from the bone marrow 2.
Bones Growth
- There is no direct information in the provided studies about the age at which bones completely stop growing in length.
- However, it is known that bone growth and development are influenced by various factors, including vitamin D and calcium intake 3, 4.
- High vitamin D and calcium intakes have been shown to increase the mineral content of growing bone in obese mice 4, but the studies do not provide information on the age at which bone growth stops.
Adipocyte Size and Obesity
- Elevated serum 25(OH)D concentrations, vitamin D, and calcium intakes are associated with reduced adipocyte size in women 5.
- High vitamin D and calcium intakes have been shown to reduce diet-induced obesity in mice by increasing adipose tissue apoptosis 3.
- Adipose tissue senescence is a common feature in obesity and ageing, and it can lead to defective adipogenesis, inflammation, and insulin resistance 6.