Medical research has identified around 150 symptoms that people may experience in the days leading up to a period. Food cravings, increased hunger, water retention, and swelling are premenstrual symptoms that may make a person feel like they are gaining weight.

Appetite changes

People may notice changes in their appetite throughout their menstrual cycle. For some, these changes may lead to concerns over weight gain.

Changes in appetite tend to occur at distinct stages of the menstrual cycle called the follicular phase and the luteal phase.

• The follicular phase. This phase begins when a person bleeds and ends before they ovulate. Estrogen is the dominant hormone during this phase. Since estrogen suppresses appetite, a person may find that they eat less during this phase.
• The luteal phase. This phase begins after ovulation and lasts up to the first day of the next period. During the luteal phase, progesterone is the dominant hormone. Since progesterone stimulates appetite, a person may find that they eat more during this phase.

Previous studies have shown that females eat more calories during the luteal phase compared with the follicular phase of the menstrual cycle.

A 2016 study found that females tend to eat more protein during the luteal phase of menstruation. Females also report increased food cravings, particularly for sweets, chocolate, and salty foods.

Not all studies show that food cravings result in an increased number of calories consumed and an increase in weight. However, people who do consume more calories as a result of their cravings may experience some weight gain.

Water retention and swelling

People may experience increased water and salt retention around the time of their period. This is due to an increase in the hormone progesterone. Progesterone activates the hormone aldosterone, which causes the kidneys to retain water and salt.

Water retention can lead to bloating and swelling, particularly in the abdomen, arms, and legs. This can give the appearance of weight gain. It may also make a person's clothes feel tighter.

However, water retention does not always signify weight gain. A 2014 study investigated water retention in females who complained of swelling during their period.

Circumference measurements taken throughout the study indicated that the participants did have significant swelling in the following areas:

• face
• breasts
• abdomen
• upper and lower limbs
• pubic areas

However, there were no significant changes in weight throughout the participant's cycles.

Many people experience both physical and psychological symptoms during a period. Symptoms may include:

People may feel additional symptoms in the days leading up to a period. Symptoms may include:

• thirst and appetite changes
• breast tenderness
• bloating
• headache
• swelling of the hands or feet

The type, severity, and duration of symptoms will vary from person to person. Additionally, some people may experience a combination of symptoms, while others may not experience any at all.

Premenstrual symptoms tend to start a few days before bleeding, or menstruation, and stop once menstruation occurs.

Medical providers can diagnose people with premenstrual syndrome (PMS) if:

• the person has a pattern of symptoms 5 days before their period for at least three cycles in a row
• the symptoms end within 4 days after their period starts
• the symptoms interfere with their normal activities

The following are some examples of how to prevent weight gain during a period.

Diet

The American College of Obstetricians and Gynecologists recommend the following eating habits to help lessen the effects of PMS:

• eating complex carbohydrates to reduce mood symptoms and food cravings
• eating calcium rich foods, including yogurt and leafy green vegetables
• reducing fat, salt, and sugar intake
• avoiding or limiting caffeine and alcoholic beverages
• keeping blood sugar levels stable by eating smaller meals more often

Supplements

A doctor may also recommend taking a magnesium supplement. This can help to alleviate the following symptoms of PMS:

• bloating
• breast tenderness
• mood disturbances

Medication

Sometimes, doctors may prescribe diuretics to people who complain of water retention during their period. Diuretics help to reduce the amount of water that the body stores.

Researchers have found that certain oral contraceptives can also help reduce water retention. In a 2007 study, females who took 3 milligrams (mg) of drospirenone and 30 micrograms (mcg) of ethinyl estradiol had reduced water retention. Nonetheless, their body weight remained unchanged.

Doctors often use combined oral contraceptives to treat the symptoms of premenstrual syndrome.

Hormonal fluctuations that occur throughout the menstrual cycle can affect a person's appetite. In particular, people may experience food cravings in the days leading up to a period.

Females may also experience water retention and bloating, which can give the appearance of weight gain.

There are several steps people can take to prevent weight gain during a period. A person can practice healthful eating habits throughout their cycle. This includes eating less salt, sugar, and fat, and stocking up on low calorie snacks to satisfy food cravings. In addition, magnesium supplements may help to alleviate bloating and other symptoms of PMS.

People who are concerned about fluid retention should talk to their doctor. The doctor may prescribe diuretics or oral contraceptives to help alleviate this symptom.