Q: Is it true that keeping exercise less intense means you are in a “fat-burning zone” that will lead to greater weight loss?
A: No. It’s true that when you walk or do other exercise at a more moderate pace, a greater proportion of the calories you burn come from fat rather than carbohydrate stored in your muscles as glycogen compared to when you run. However, in the same amount of time, more intense exercise burns more total calories and that includes overall burning of more fat.
Exercise physiologists tell us to ignore the labels on treadmills and equipment referring to a “fat burning zone.” Don’t push yourself to an intensity that is unsafe for you — talk with your doctor if you have any question of what that might be, based on your age and health conditions. But if it is safe for you, don’t feel that you need to hold back from vigorous exercise that allows you to burn more calories in less time and also can bring significant fitness gains. Weight loss efforts will be enhanced, not hurt.
Q: Is green tea really that much healthier than regular black tea? I want the health benefits, but prefer the flavor of black tea.
A: Most of the laboratory studies have investigated compounds, especially EGCG, primarily in green tea. However, although green and black teas contain a different balance of phytochemical compounds, according to USDA analysis, green tea is only slightly higher in antioxidants than black tea.
In laboratory studies, green tea and its EGCG can decrease growth of cancer cells and stimulate their self-destruction. Human studies are less clear in showing cancer protection. For decreasing risk of heart disease, human studies so far do show more benefit from green tea than from black tea. One big problem, though, many of the green tea studies are conducted in Asia where more people drink green tea frequently. So the benefits seen may somehow include the effect of lifelong green tea consumption (as opposed to the effects of starting to drink it in middle age or later) and may also reflect other aspects of an Asian diet that researchers may not have been able to adjust for in analyzing the data.
Green tea is a great health-wise beverage choice, but for now, the evidence is still somewhat unclear about its benefits or how much we need to drink to attain them. You may like to try other forms of green tea, perhaps with some additional fruit or spice flavoring. Yet if you truly prefer black tea, enjoy it and know that you are getting healthful compounds there, too.