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Middle age is a time of transition, and it can catch some people off-guard. By age 40, many adults are surprised at changes in their health. It is not unusual to see some weight gain or problems like high cholesterol, insulin resistance, or high blood pressure brewing. 

These metabolic changes are common, and if left unmanaged, they can impact long-term health and well-being. Learn what is at the root of middle-aged health changes and the best ways to protect health and wellness after 40.

Physical Changes After 40

One significant change that accompanies middle age is the gradual loss of muscle mass with fat gain, especially in the abdominal region. Studies suggest that for most people, body fat increases by about 1% each year after 40.1 That shift in body composition during middle age leads to changes in metabolism. As a result, weight gain of about one pound per year is common between the ages of 40 and 66.1 

Declining levels of sex hormones, such as estrogen and testosterone, account for much of the body composition changes. In young adulthood, these hormones promote muscle growth. As levels start to decline around age 40, it becomes harder for men and women to build and maintain muscle. Additionally, women, especially, experience a loss of bone density as they approach menopause and afterward. 

Diet and a more sedentary lifestyle also play important roles. Those with families may eat on the run more often, with fast food, take-out dinners, or less-than-healthy options as their go-to choice. Empty nesters may dine out more frequently and indulge in rich meals, desserts, or alcoholic beverages. Often, exercise takes a backseat to other activities as you get older. These habits tend to promote more fat gain and muscle loss.

Middle Age and Metabolic Health

Muscle tissue is vital for healthy glucose and fat metabolism. As you age and muscle is replaced with fat, insulin cannot work as well as it should. Insulin is the hormone responsible for shuttling glucose from the bloodstream into cells. Insulin resistance, a condition in which cells do not respond well to insulin, becomes more common in middle age. Often, it is a precursor to diabetes. 

Additionally, more fat is stored deep within the abdominal cavity, surrounding the liver, stomach, intestines, and other organs. Known as visceral fat, this belly fat is more than cosmetic. It promotes chronic, low-grade inflammation, which increases the risk of these and other health problems common during middle age:

  • Diabetes or prediabetes.
  • High blood pressure. 
  • High cholesterol and heart disease.
  • Metabolic syndrome. This is when three or more of the following: high triglycerides, low HDL (good) cholesterol, high blood sugar, excess abdominal weight/girth (increased waist circumference) and high blood pressure occur together, increasing your risk of heart disease, stroke, and diabetes.
  • Nonalcoholic fatty liver disease.
Gut Health and Metabolic Changes

Some research also suggests a link between the gut microbiome, the trillions of bacteria, viruses, yeasts, and other microbes in the digestive tract, and obesity or changes in metabolic health.2,3 The gut microbiome plays many essential roles in health, including supporting immunity, strengthening the intestinal lining, and promoting a normal response to inflammation. 

There is no consensus on what makes a “healthy microbiome.” However, scientists agree that a rich, diverse microbiome is generally associated with good health. A more diverse microbiome has ample beneficial bacteria to keep pathogens in check. Beneficial gut bacteria also produce various health-promoting compounds, including short-chain fatty acids (SCFAs), which can mediate inflammation and support immune health.2 

When there is an imbalance in the microbial mix with a loss of diversity, fewer beneficial bacteria and more pathogenic or opportunistic bacteria are often present. This state, called dysbiosis, is linked with an increased risk of many chronic health conditions. Researchers have noted unfavorable microbiome changes, with more pro-inflammatory and fewer anti-inflammatory bacteria in people with obesity and diabetes.2 

The gut microbiome composition is dynamic and can change over time in response to internal or external stressors. It can be disrupted during middle age, or any time, by these and other factors:

  • A diet low in plant foods and fiber.
  • Ultra-processed foods, including fast food, packaged meals and packaged sweet or savory snacks.
  • Excess sugar and alcohol.
  • Certain medications, particularly antibiotics.
  • Chronic stress.
  • Sedentary lifestyle.
  • Poor sleep.
  • Exposure to environmental toxins.

 

Combating the Effects of Aging

Changes to your body and metabolic health are inevitable as you age. However, establishing healthy habits related to your diet and lifestyle can help minimize and manage them. These strategies can help maintain a healthy weight, minimize body composition changes, and support microbiome health in middle-aged adults.

Diet recommendations during middle age

A healthy diet is a cornerstone of healthy aging. One way everyone can improve their diet is to add more plant foods such as fruits, vegetables, legumes (beans), nuts, seeds, and whole grains with each meal and snack.

Plant foods are important sources of antioxidants that support cellular health and reduce oxidative damage. They also support healthy weight by providing ample amounts of fiber, which is filling and low in calories. Additionally, a high-fiber diet promotes healthy glucose metabolism, insulin response, and cholesterol levels. A plant-forward diet also supports gut health because it is rich in prebiotics, compounds that promote the growth and activity of beneficial gut bacteria.

A large body of research shows that plant-forward diets such as vegetarian or Mediterranean diets are associated with lower rates:4

  • Heart disease
  • Hypertension
  • Type 2 diabetes
  • Metabolic syndrome
  • Colon and lung cancer

Protein becomes even more critical during middle age and beyond because it enhances the effect of strength training exercises on muscle strength, helping to maintain muscle tissue as you age.1 Experts recommend eating up to 1.2 grams of protein per kilogram (approximately 0.5 g per pound) of body weight in middle and old age.5 Ideally, protein should be spread evenly throughout the day and come from plant or other lean sources such as:
 

  • Legumes such as chickpeas, lentils, black, kidney, or pinto beans
  • Tofu or tempeh
  • Nuts and seeds or nut butter
  • Eggs
  • Greek yogurt
  • Poultry
  • Fish or seafood

Cultured and fermented foods, such as yogurt, kefir (cultured milk), sauerkraut, and kimchi, contain live bacteria that add to the gastrointestinal tract's beneficial bacteria. Eating one or more servings of these foods daily can support gut health during middle age. Those who do not eat these foods regularly may consider a probiotic that supports digestive, and metabolic health or a synbiotic supplement that combines probiotics with prebiotics.

Finally, a healthy diet is one based primarily on whole foods. Nutrition experts recommend avoiding or limiting highly processed foods such as fast foods, frozen or packaged, prepared meals, and packaged sweet or savory snacks. These are often high in refined fats, sugar, and artificial ingredients, which may cause disruptions in the gut microbiome and worsen inflammation. Diets high in these foods are also linked with obesity, diabetes, and hypertension.6 

Lifestyle modifications for middle-aged adults

A healthy lifestyle is also essential in middle age. Focusing on these healthy habits can make a significant difference in health and wellness now and in the future:
 

  • Stay physically active. Exercise has many benefits, including managing weight, promoting healthy glucose metabolism, supporting gut health, and improving mental health. All adults should aim for at least 30 minutes of moderate physical activity most days of the week. This should include aerobic exercises such as walking, hiking, biking, gardening, or playing a sport. Strength training two to three times weekly is also crucial at this stage of life as it helps to maintain muscle and support a healthy metabolism. 
  • Manage stress. Stress from family, financial, and job-related demands is prevalent during this stage of life. But when stress becomes chronic, it affects hormones, triggers inflammation, and promotes insulin resistance, abdominal obesity, and hypertension. Yoga, meditation, exercise, sound healing, and talk therapy are all helpful tools for managing stress. A quality stress support supplement can also help the body respond to stress in a healthy way and maintain balanced cortisol and other hormone levels. 
  • Get adequate restorative sleep. Sleeping at least seven to nine hours each night is one of the best ways to support good health at any age. Poor or inadequate sleep increases the risk of many health problems, including heart disease, stroke, metabolic syndrome, and diabetes. It may also promote unhealthy changes in the gut microbiome.

Unfortunately, insomnia or disrupted sleep is common during middle age because of stress, jet lag in those who travel, hormonal changes (especially among women approaching menopause), sleep apnea, and other issues. Good sleep hygiene is essential during middle age. It starts with establishing a consistent sleep and wake schedule, turning off electronics 30 to 60 minutes before bedtime, dimming the lights, and practicing a relaxation activity to wind down each night. Magnesium and botanical-based sleep support supplements may promote faster time to sleep and better quality sleep.8

Middle age is an important turning point in life when health problems begin to appear. It is worth taking the time to assess diet, lifestyle, and health habits. Any improvements made now will reward you with better health in the future.