In your forties, your body may have an increasingly difficult time digesting carbohydrates, which may lead to weight gain. Living a stressful life can lead to an increase in the stress-hormone called cortisol, which can make you more prone to gaining belly fat. Estrogen loss may also lead to fat redistribution in your body and cause belly fat gain.11
As you enter your forties, you are also entering perimenopause, when levels of your sex hormones progesterone and estrogen decline. Besides regulating your menstrual cycle and reproductive functions, these hormones also impact restful sleep and relaxation. A decrease in progesterone and estrogen levels may lead to sleep disturbances, restlessness, and insomnia.1 Because changes in sleep patterns have been associated with weight gain, sleepless nights may make weight loss increasingly difficult.2
Soda and other sugary soft drinks are all empty calories that may result in weight gain and health problems. Don’t be fooled—diet soda is not better. It’s full of artificial sweeteners, preservatives, and often caffeine that can disrupt your health.31,32 It can interfere with your hunger hormones, increase your appetite, and lead to weight gain.33,34 Herbal teas and green juices are a good option.
If you eat healthy and exercise regularly and still can’t lose weight, your thyroid might not be working like it should. This happens in about 5% of people, and it's most common in women and people over 60. In addition to weight gain, it can also cause fatigue, joint or muscle pain, and depression. Medications can help, so get it checked if you think it might be an issue.