What people believe
The idea that pregnancy means doubling your food intake is one of the most persistent beliefs in prenatal culture. It gets passed down through generations, reinforced by well-meaning family members, and used by food marketing to justify indulgence. The underlying logic seems intuitive — there are two of you now, so you need twice the food.
What the evidence says
You do not need twice the calories. You barely need any additional calories in the first trimester. ACOG's guidance is specific: most pregnant women need approximately 340 additional calories per day in the second trimester and 450 additional calories per day in the third trimester.1 In the first trimester, caloric needs do not increase at all for most women.
To put 340 calories in perspective, that is roughly a banana with two tablespoons of peanut butter, or a small bowl of yoghurt with fruit. It is not a second dinner.
The 2020–2025 Dietary Guidelines for Americans echo this, emphasising nutrient density over quantity: the additional calories should come from nutrient-rich foods, not simply more food.2 Excessive weight gain during pregnancy is associated with increased risk of gestational diabetes, preeclampsia, caesarean delivery, and macrosomia (a larger-than-average baby), all of which carry their own clinical risks.3
What does increase substantially during pregnancy is the need for specific nutrients — iron, folic acid, choline, iodine, calcium, and omega-3 DHA — which is why prenatal vitamin selection matters far more than total caloric intake.
What to do instead
Focus on nutrient density rather than volume. Track the quality of what you eat rather than trying to eat more. If you are at a healthy weight before pregnancy, a total weight gain of 11.5–16 kilograms (25–35 pounds) is the ACOG-recommended range for a singleton pregnancy, though this varies by pre-pregnancy BMI.1