Regular Exercise Trumps the Obesity Gene
How Physical Activity Increases Fat Oxidation To Keep You Slim
Sep 19, 2009
Andrew Hattersley and his colleagues at the Peninsula Medical School in Exeter, England discovered a gene variant called the FTO gene; an allele that is strongly linked with body mass index (BMI). They claim that persons who inherited two (2) copies of the "fat" gene, or those with 1 copy of the gene are more susceptible to obesity than people who do not carry the gene(s). The genetic predisposition to obesity is approximately 1 in 10,000 people.
Researchers believe that obesity is influenced by genetic inheritance. However, they also believe that healthy lifestyle factors such as regular physical activity, eating a healthy diet, avoiding risky/addictive activities (smoking, taking addicting drugs, etc.) have a greater salutary impact on health than mere heredity in the long run. The Hattersley study was published in the 2007 issue of Science.
If obesity runs in families, then its most dramatic expression will be seen in same-sex twins carrying the FTO gene.To determine the effect of physical activity on genetic inheritance, Leskinen and his team studied the effects of physical inactivity against a healthy lifestyle on 16 middle-aged (50-74 yr) same-sex twins for over 30 years. The twins in the trial had a history of discordance for physical activity that is; one person is active, while the other is sedentary. The participants were selected from the Finnish Twin Cohort Study (TWINACTIVE Study).
Results: The physically inactive co-twins had 50% greater visceral/abdominal fat than the active co-twins. They also have higher liver fat content (170% more) than their counterpart, and their intramuscular fat is 54% higher than their active co-twins. This suggests that physical activity is an important criteria in preventing the accumulation of the high-risk fat overtime even for those with genetic liability for obesity. The trial was published in the 2009 online edition of the International Journal of Obesity
Burning More Fat Than Glucose
When people exercise, it is usually to burn or lose "fat," rather than glucose. The fact is glucose and fat are both used up during exercise - glucose first, then fat. During the first few seconds of intense exercise like sprinting, playing raquetball, or squash, muscle glucose is used. This reserve is present in very small amounts and when it is depleted, the body turns to blood glucose for fuel. When blood sugar levels begins to dip, the liver converts glycogen (animal starch) to glucose to maintain normal blood glucose values. When liver stores are used up, then the body begins to use fat for fuel. That's after about 60 minutes of physical activity. Why? Because glucose is the body's primary or "preferred" fuel. So to burn more fat, fitness experts recommend the following strategies:
- Engage in low-intensity to moderate-intensity aerobic activities for longer periods of time, preferably at least 60 minutes. Go slow, go steady, but keep going for about an hour. Walking moderately for 60 minutes, cycling, swimming, elliptical training, gardening, are some examples of low to moderate intensity endeavors.For people with diabetes, don't worry about bringing your blood sugar down. It will go down even if you're only doing a low-intensity workout. Remember - sugar goes first!
- Exercise everyday or at least most days of the week. Regular exercise brings about beneficial changes or adaptations in the body (increases the number enzymes that burn fat, increases the cells' ability to burn fat, and increases the muscles' sensitivity to insulin so a little insulin goes a long way, correcting hyperinsulinemia - high levels of insulin in the blood: a hallmark of type 2 diabetes).
- Eat a low-glycemic index and low-fat foods before and after workouts. A low-glycemic index food will not cause your blood sugar to surge. If your pre-workout meal is high in carbohydrates, fat that is supposed to be burned is spared. Also dietary fat takes longer to become available for the body to use as fuel, generally about 3-4 hours.
Genetic inheritance exerts a profound influence on health. However, many health experts are convinced that it's not the hand you're dealt, but rather how you rise to the challenge that wins out in the end.
References
Hattersley AT et al. "A Common Variant in the FTO Gene is Associated with Body Mass Index and Predisposition to Childhood and Adult Obesity" Science May 2007;316(5826):889-894
Leskinen T et al. "Leisure-time physical activity and high-risk fat: a longitudinal population based twin study"
International Journal of Obesity Published online ahead of print September 1, 2009
Stevenson E et al. "Fat Oxidation During Exercise and Satiety during Recovery Are Increased Following a
Low Glycemic Index Breakfast in Sedentary Women" J Nutrition May 2009; 139(5):890-897
Benning JR & Steen SN "Fats as Fuel During Exercise" Nutrition for Sports and Excercise, Second EditionJones & Bartlett Publishers 1998 pp:65-70
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