After 40, your hormone levels (estrogen) drop. This causes your insulin (hormone that helps your body use sugar) rise. Your thyroid levels go down. This combination makes you hungrier. You end up eating more and burning fewer calories. Much of the weight gain occurs around your belly. Eat more foods with fiber (berries, whole grains, nuts) to fill you up and help you eat less. Aim for 25 grams of fiber each day after the age of 40. Other ways to increase your metabolism include:
Most vegetarians eat milk products and eggs, and as a group, these lacto-ovo-vegetarians enjoy good health. A healthful vegetarian diet falls within the food pyramid guidelines offered by the USDA. However, meat, fish and poultry are major sources of iron, zinc and B vitamins, so pay special attention to these nutrients. Vegans (those who eat only plant-based food) should consult a health care professional about adding vitamin and mineral supplements; make sure you consume sufficient quantities of protein, vitamin B12, vitamin D and calcium.
Potdar RD, Sahariah SA, Gandhi M, Kehoe SH, Brown N, Sane H, Dayama M, Jha S, Lawande A, Coakley PJ et al. Improving women's diet quality preconceptionally and during gestation: effects on birth weight and prevalence of low birth weight—a randomized controlled efficacy trial in India (Mumbai Maternal Nutrition Project). Am J Clin Nutr  2014;100(5):1257–68.
  Community centers (including banks, town halls, post offices)    ↑ knowledge about health and nutrition, ↑ food expenditures, ↑/NC food share, ↑ HH food consumption, ↑ dietary diversity, ↑ intake of MN (except for heme-Fe), ↑ HH intake of fruits, vegetables, and ASF, ↑/NC intake of fats and sweets, ↑ weight gain (greater among high BMI), ↑ participation in social networks, ↑ self-confidence, ↑ control over resources  ↑ knowledge about health and nutrition, ↑ HH food security, ↑ food expenditures, ↑/NC food share, ↑ HH food consumption, ↑ dietary diversity, ↑ HH intake of fruits, vegetables, and ASF, ↑/NC intake of fats and sweets, ↑ participation in social networks, ↑ self-confidence, ↑ control over resources, ↑ ANC coverage  ↑ knowledge about health, NC hypertension, ↓/NC missed meals, NC food sufficiency, ↑ health care utilization 

You should eat a healthful, well-balanced diet during pregnancy. However, you should avoid certain foods, including raw or undercooked fish, poultry and meat; raw or partially cooked eggs or foods containing raw eggs; unpasteurized juices; raw sprouts; unpasteurized milk products; and some soft cheeses (cream cheese is OK). Avoid deli meats and frankfurters unless they have been reheated to steaming hot before eating. To prevent food-borne illnesses, take the following precautions:

When you’re at the bar or a party and starving, your options aren’t always the best. But if it’s bruschetta, chips and salsa, or wings, go for the chicken (though nuts would be even better). Protein fills you up faster than carbs do, making it less likely that you’ll overeat, says Christopher Ochner, Ph.D., a research associate at New York Obesity Nutrition Research Center at St. Luke's Roosevelt Hospital Center. And since it’ll keep you satiated longer, you won’t be as tempted when your friend orders a brownie sundae or brings out a tray of blondies.
When you do high-intensity interval training (and if you’re not, you should be!), follow a 2:1 work-to-rest ratio, such as sprinting one minute followed by 30 seconds of recovery. [Tweet this secret!] According to several studies, the most recent out of Bowling Green State University, this formula maximizes your workout results. The BGSU researchers also say to trust your body: Participants in the study set their pace for both running and recovery according to how they felt, and by doing so women worked at a higher percentage of their maximum heart rate and maximum oxygen consumption than the men did.
Young adults. Teen girls and young women usually need more calories than when they were younger, to support their growing and developing bodies. After about age 25, a woman’s resting metabolism (the number of calories her body needs to sustain itself at rest) goes down. To maintain a healthy weight after age 25, women need to gradually reduce their calories and increase their physical activity.
For girls and adult women, educational interventions are considered a powerful means of improving their health and nutritional status throughout their lives. Education level is often associated with maternal caregiving practices and the nutritional outcomes of their children (174, 175). Few studies, however, evaluated the impact of education as an intervention on women's nutrition outcomes. Instead, many studies used survey data and reported on associations between education and nutrition. For instance, in low- and middle-income countries, higher levels of education were associated with lower prevalence of underweight and higher prevalence of overweight among women (176, 177). However, this depended on the type of employment in which women participated (178, 179). In addition, in many high-income settings, the converse was true (177). Level of literacy was also associated with improved anthropometric measures. In southern Ethiopia, literate mothers were 25% less likely to be undernourished than were illiterate women (180). One econometric analysis suggested that doubling primary school attendance in settings with low school attendance was associated with a 20–25% decrease in food insecurity (181). Overall, though, these associations were limited in their ability to draw conclusions about causality and the effect of education interventions on nutrition outcomes.