Diet for a Woman in Her Early 30s

Once you turn 30 years old, there are changes in your body that can have an effect on what nutrients you should include in your diet. A balanced diet for a 30-year-old woman should include food sources that help build lean muscle mass and support bone strength.

The Office of Disease Prevention and Health Promotion's 2015-2020 Dietary Guidelines for Americans has an age and diet chart that advises women in their 30s to consume between 1,800 and 2,200 calories. This is slightly lower than a healthy diet for a 20-year-old female, which is recommended to fall between 2,000 and 2,400 calories.

The lower end of the range is for sedentary adults, while the upper range is for active individuals, or those who walk more than 3 miles a day at 3 to 4 miles per hour.

A healthy diet for a 30-year-old female should focus on certain nutrients and food sources to compensate for bodily changes starting around age 30. These include foods to help build lean muscle mass, strengthen bones and prevent diseases.

Between ages 20 and 30, people are at their maximum physical capacity, and after that, muscle mass and strength decrease. In fact, after the age of 30, adults lose 3 to 8 percent of their muscle mass per decade. The loss of muscle mass due to aging is called sarcopenia, and if muscle mass is not maintained, it can lead to future problems and reduced quality of life, such as frailty or injuries or trauma from a fall.

Read more: Your Ultimate Guide to Gaining Lean Muscle

Both exercise and nutrition are important for building muscle strength and slowing muscle loss. For example, resistance or strength training can help increase lean body mass, increase metabolic rate and build back muscle that is lost with aging.

Protein: Protein is an important macronutrient found in muscles, skin, bones, hair and body tissues. It is made up of various amino acids that the human body doesn't produce itself, so protein needed for your body has to come from food.

Various protein sources can provide essential amino acids for the body to help with muscle mass. The Dietary Guidelines recommends 0.8 grams of protein per kilogram of body weight, or around 46 grams total a day, for adult women ages 31 to 50.

Protein can be both "complete," in which it contains all nine essential amino acids, or "incomplete," where it is missing a least one of them. However, you can combine incomplete protein sources to consume all the amino acids necessary for your body.

Read more: 5 Tips for Eating Protein the Right Way

Complete protein sources include animal meats such as beef, poultry, seafood, eggs and pork. Incomplete protein sources include proteins from plants, vegetables, grains, nuts and legumes. Some research has shown a link between red meat and increased health risks. For example, an April 2012 study in JAMA Internal Medicine showed an association between eating red meat and an increased risk of cardiovascular, cancer and total mortality.

Women in their 30s should consume protein from leaner animal sources such as seafood, eggs or white meats, or combine incomplete proteins from sources like beans, vegetables and whole grains. Protein powders and supplements are also available if you can't get enough protein from food.

Vitamin D: Vitamin D is important for bone metabolism, and per a March 2015 study in BioMed Research International, vitamin D can support muscle strength and function. Thus, women in their 30s should consume vitamin D through food sources or supplements.

The National Institutes of Health (NIH) recommends adults have 600 International Units of vitamin D up until the age of 70. Sunlight is a natural source of vitamin D, and good food sources include egg yolks, saltwater fish and liver. Always consult a doctor before adding any supplements to your diet.

Omega-3 Fatty Acids: Omega-3 fatty acids have been linked to cardiovascular health and a June 2016 report in Current Nutrition Reports showed they were also linked to muscle strength. Good sources of omega-3 fatty acids are found in seafood and fish products such as salmon (both farmed and wild), anchovies and halibut. There are also omega-3 supplements such as fish oil.

Read more: When Is the Best Time to Take Omega-3 to Avoid Side Effects?

According to the National Institute on Aging, sometime around age 30, bone mass stops increasing. The goal is to preserve as much bone mass as possible to reduce the risk of osteoporosis, a disease that weakens bones to the point where they break easily. A healthy diet for 20-year-old women should include both calcium and vitamin D in order to ensure bone formation is supported during the years it is still growing.

After maximum bone mass is reached in the late 20s, a balanced diet for a 30-year-old woman should also include both calcium and vitamin D in order to maintain bone mass and strength. The NIH recommends adults 31 to 50 years old consume 1,000 milligrams of calcium a day. Good source of calcium in foods include the following:

• Dairy products such as milk and yogurt
• Dark green, leafy vegetables such as spinach and broccoli
• Sardines and salmon with bones
• Tofu
• Almonds
• Foods fortified with calcium like orange juice and cereals

Vitamin D is another important nutrient to help with bone mass, and it also helps with the absorption of calcium. If you are unable to get the daily recommended intake of calcium or vitamin D from foods, you can also take supplements.

According to an April 2014 review article in BioMed Research International, one of the main theories is that aging is due to the build up of oxidative damage in the body caused by free radicals. One way to combat the stress of free radicals on your tissues and organs is to consume antioxidants. While this is beneficial at any age, antioxidant intake should be a focus in your 30s to help mitigate the accumulated effects of free radicals later in life.

Read more: High Antioxidant Fruits & Vegetables

Foods that could have anti-aging benefits include:

• Green and black tea
• Apples
• Blueberries
• Soybeans
• Back rice

Due to changes in the body such as muscle loss, hormonal changes and increases in body fat, metabolism also starts to slow down with age. Between ages 30 and 70, there is an increased likelihood of obesity.

Because of a slower metabolic rate, losing weight in your 30s requires more carefully managing your energy balance, or how many calories you consume vs. how many you expend. This can be achieved with both diet and exercise.

Total energy expenditure includes resting metabolic rate (how many calories you need for basic body functions), the thermic effect of food (how many calories are burned through digestion) and activity energy expenditure (how many calories are burned through physical activity).

Read more: The One Food Scientifically Proven to Boost Metabolism

A negative energy balance, or eating fewer calories than you burn, can contribute to weight loss. However, continually cutting calories is not a sustainable weight loss strategy. An August 2015 study in the International Journal of Obesity showed metabolism adjusts accordingly during calorie restriction. Instead, women should focus on engaging in regular physical activity and a healthy diet that incorporates whole foods and protein to build female muscle.