Metabolism changes in the third trimester

• Pregnancy Tracker App
• Articles

By the third trimester, your body is getting ready for birth. Thus, it is not just nourishing your growing baby. It also makes complex internal metabolic and hormonal shifts.

Metabolism, which controls how your body converts food into energy, speeds up significantly during the final stretch of pregnancy. This is to meet the intense demands of a baby nearing full term.

Why Your Body Needs More Energy Now

In the third trimester, your baby is growing rapidly. Organs are maturing, fat accumulates under the skin, and the brain is developing quickly. To support all of this, your body needs to deliver more nutrients and oxygen.

Your basal metabolic rate — the amount of energy your body uses at rest—increases significantly in the third trimester. Even if you’re not doing anything physically strenuous,

your body is still burning more calories than before. That’s because your heart is pumping more blood, your lungs are working harder, and your kidneys are filtering increased fluid.

You may notice that you’re hungrier more often. This is your body’s way of asking for more fuel to keep up with all the extra work. However, this doesn’t mean you need to eat excessively—just more mindfully.

How Hormones Influence Your Metabolism

Hormones play a major role in metabolic changes during late pregnancy. Insulin resistance increases naturally in the third trimester. This allows more glucose to remain in the bloodstream so the baby can access it easily.

While this is normal, it can sometimes become too pronounced, leading to gestational diabetes. That’s why glucose screening typically happens in the second trimester, but close monitoring often continues into the third.

If your blood sugar levels remain within a healthy range, your body uses this glucose efficiently to nourish the baby. But if insulin resistance becomes too high, it can affect both you and your child’s health. That’s why a balanced diet rich in fiber, lean protein, and healthy fats is essential.

Fat Storage and Energy Reserves

Your body also stores more fat in the third trimester, even if your weight gain slows down compared to earlier months. This is a protective mechanism. Labor, delivery, and breastfeeding require enormous energy; your body prepares for these tasks by building reserves.

Interestingly, even if you feel more tired or less active, your body continues working behind the scenes to break down nutrients, regulate hormones, and provide steady energy to your baby.

Adapting to Your New Metabolic Rhythm

Listening to your body is key. You may find you need to eat smaller, more frequent meals instead of large ones. This helps avoid energy crashes and keeps your digestion comfortable as the baby presses on your stomach. Staying hydrated also supports metabolic function and helps reduce swelling.

You don’t need to count calories obsessively, but focusing on nutrient-dense foods makes a big difference.

As your body prepares for labor and the incredible work of bringing a new life into the world, these metabolic shifts are not just natural but necessary.