As we age, we lose muscle.
NUTRITION Though still strong, even Jack LaLanne lost muscle tone in his later years. You have heard of the middle-age spread. But it's now apparent in society and from a recent research study that there may be a direct correlation between protein consumption, muscle atrophy and obesity.
The study led by Dr. George A. Bray, MD, included 25 men and women restricted from much exercise who lived in a carefully controlled research facility for three months.
Those in the low-protein group stored about 90 percent extra daily calories as body fat while losing 1.5 pounds of lean body mass. The other groups saw 50 percent of the added calories became fat. Those with high-protein intake, gained an average of 6.5 pounds of muscle mass. 
What Is Adequate Protein
According the FDA, the minimum recommended protein amount is 46 grams per day for women and 56 grams per day for men—about 5 to 6 ounces of protein-rich food.  To maintain muscle mass, Bray and his team learned study participants had to consume at least 78 grams of daily protein—40 to 70 percent more.
These findings are particularly important to vegetarians and vegans who might frequently forego a balanced meal in favor of steamed vegetables or a field-greens salad with vinaigrette dressing. Simply eliminating meat—red or otherwise—does not make one healthy. It is important to monitor daily protein consumption.
A bowl of cereal with almond milk provides about 1 gram of protein. By way of contrast, a breakfast of two veggie bacon strips, a two-egg omelette with mozzarella cheese, two tomato slices  and a cup of almond milk provides about 23 grams of protein. As you can see, with two meals to go, this is not even a third of what Bray found necessary. Vegetarians may consider protein powder supplements.
It should be noted that those with chronic kidney disease (CKD) should limit their protein intake. If you eat lots of protein and have CKD, you may want to make a few changes because a high protein diet is hard on your kidneys. On the other hand, a diet too low in protein is even worse for you. 
Of course, staying fit is not all about eating protein. One must moderate carbohydrate consumption and maintain a regular exercise routine. Metabolic disorders can also contribute to weight gain. ClinicalPosters.com offers several posters in the diet category that help nutritionists, dietitians and physicians educate patients on proper nutrition.
- Too little protein may equal too much body fat. health.com
- How Much Food from the Protein Foods Group is Needed Daily? choosemyplate.gov
- High Protein Vegetables. highproteinfoods.net
- 8 tips for starting a low protein diet if you have chronic kidney disease. davita.com