AP Biology class blog for discussing current research in Biology

Tag: calories

Can eating less save your life????

Nutrition and calories have been a topic of much discussion over the past few years.  In a recent study by Yale University, results show that a diet with less calories than the recommended amount can increase longevity.

In this study, researchers at Yale asked participants to eat a diet with a certain amount of calories that is recommended to them based on their weight. They then asked a few people to lower their calorie intake by 14% . The results were extremely positive. The immune system is fueled by the thymus gland. In this gland  T-Cells are produced, which are an essential part of the immune system;  the body will die without them. One of the main issues that come with the human body with age is fat buildup in the thymus gland. This fat buildup happens fast, and the thymus becomes almost fully deactivated when filled up with fat. This means that less T-Cells will be produced.

T-Cells are vital to the body’s function. There are two types, Cytotoxic T-Cells and Helper T-Cells. The Cytotoxic T-Cells kill infected cells and certain types confer future immunity to antigens, and the Helper cells activate other immune system cells. When these pieces are removed, the whole system falls apart, and the body can get infected easier. This is why any change to one’s life that can increase the activity lifespan of the thymus is very important.

T-dependent B cell activation

This all is connected to the PLA2G7 protein in the body, which is created by macrophages, another important type of cell in the immune system. Inhibition of the protein targets inflammation that causes the fat buildup which stops the thymus from working. This is done through calorie restriction, which alters the gene for this protein.  Even now, inhibiting PLA2G7 is being talked about as a potential prostate cancer drug.

Overall, this study shows that there is hope. This protein’s effects may change the way people eat and live. While decreasing calories has positive effects, as long as one consumes a healthy diet, there will be plenty of health benefits. It is important to go at a dieting pace that fits every body differently.

Exercising in the “Extremes” (Hot or Cold) Does Not Necessarily Lead to Weight Loss. Here’s What Does:

As it has been a trend for years, many believe the claim that exercising in cold or hot temperatures will cause you to burn more calories, leading to weight loss. Although many believe this, it is not actually true nor an efficient way to lose weight. 

First, let me take you through how humans burn calories. The most common way you burn calories is by your metabolism. According to the Mayo Clinic, “metabolism is the process by which your body converts what you eat and drink into energy. During this complex biochemical process, calories in food and beverages are combined with oxygen to release the energy your body needs to function.” Metabolism can also be classified as your basal metabolic rate, or how many calories your body uses to carry out these functions. The basal metabolic rate makes up about 60 to 80 percent of your total energy expenditure and calorie loss. In addition to your metabolism, a portion of your energy expenditure and therefore loss in calories comes from thermogenesis: the way in which the body produces heat. Thermogenesis makes up 10% of total energy expenditure, leaving only 10-30% for physical activity (which, in reality, is not a lot). 

In terms of that last 10-30%, the body burns the remaining calories by shivering (if cold) or by exercising. Shivering and exercise are viewed as the same inside of the body as they both trigger the activation of what is called brown fat or brown adipose tissue. When you shiver, your muscles involuntarily contract to generate warmth to regulate homeostasis but it also triggers “muscles to secrete a hormone that stimulates energy use in brown fat cells” (according to the National Institute of Health). The same thing happens when you exercise! In another example, brown fat helps infants who don’t know how to shiver yet regulate their body temperature. 

While brown fat burns calories to generate heat, something called white fat stores calories as heat / insulation to keep you warm. As you can assume, It is better to have more brown fat than white fat as large amounts of white fat, and this insulation, can lead to obesity. This is because white fat stores energy in large lipid droplets throughout the body. On the other hand, brown fat contains smaller lipid droplets and higher amounts of mitochondria. This increase in mitochondria causes an increase in ATP or energy production and therefore increase in energy expenditure and calorie loss. 

So how is this related to energy expenditure and calorie burning, you ask? Many people believe that you can burn more calories in the cold because of this brown fat. Although this is true, you need at least 2 hours in 66 degrees fahrenheit (or lower temperature) in order to see the extreme effects of the body activating the brown fat and burning more calories. On the other hand, many believe that you will burn more calories in the heat (or hot conditions) because sweating more must mean your body is working harder and losing more calories, right? This is not always the case – releasing more sweat doesn’t always mean you are releasing more energy and losing more calories. Rather, in the case of very hot conditions, like hot yoga for example, the sweat you are releasing only causes you to lose more water, not calories.   

There are pros and cons to any type of exercise, but ultimately choosing to work out in hot or cold conditions to promote weight loss, may do more harm for you than good, especially if you are new to the exercise scene as your body may not react well to these temperatures. To promote weight loss, you must be in a calorie deficit –  burning more calories than you are in consuming. This is the best and really the only way to lose weight (along with exercise). 


You Are What You Eat


Whenever a person consumes healthier meals and therefore less calories, according to a new study on mice at the NYU Langone Medical Center, they could be lengthening their lives.

Using female mice, scientists fed one group of mice a diet of pellets containing a high amount of calories, while feeding another group of mice a diet of pellets containing 30% less calories. The hippocampus and the region surrounding it in the brains of the mice were then examined for expression of aging-genes throughout various stages of maturity. The results of the study, while not entirely applicable to humans, has shown that the mice that ate the lower calorie diets had less expression of aging genes and had less risk of chronic illnesses such as hypertension and stroke.

“The study does not mean calorie restriction is the ‘fountain of youth,’ but that it does add evidence for the role of diet in delaying the effects of aging and age-related disease.” Stated Stephen D. Ginsberg, a researcher involved with the study. The study examined more than 10,000 genes related to aging, which is a much larger amount than that previously studied by researchers. While the study was performed on mice, the results could be similar in humans, and the researched performed by Dr. Ginsberg and others should serve as a warning for our ever-indulgent world of fast food and high caloric intake.


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