If one is underweight but has some belly fat, what are healthy approaches to getting a flat stomach?

All types of fat don't actually make you fat. If you have a belly that you're finding hard to get rid of, despite a low-fat diet; chances are, you're consuming a lot of carbohydrates.  Lemme break it down.
There are two types of carbohydrates.
  1. Simple carbs – Composed only of sugar (glucose and fructose) which break down much faster in the body leading to fast and increased blood sugar levels. 
  2. Complex carbs – Carbs that have a more complex sugar structure - contain fiber, vitamins and mineral which take a longer time to digest which means, the rise in blood-sugar is slower and gradual.
When we eat, Insulin is released from our pancreas, signalling that the body has just been fed. It travels in the blood stream and opens up the cells (in various muscles and tissues) in our body to transport the required amounts of glucose (blood-sugar) to them. At this point, our body starts using the nutrients that we've just consumed and stops burning the stored fat.
These cells need only a certain amount of glucose and cannot store everything that has been consumed. Once these cells fill up, the transport is stopped and all of the remaining blood-sugar that HAS TO BE put away somewhere, is driven into the adipose tissues in your body a.k.a fat cells i.e. insulin now drives accumulation of fat.
RECAP: Simple carbs are broken down faster and spike your insulin levels higher. Higher your insulin levels, more fat gain over time.
Something that not a lot of us know about is what they call ‘Glycemic Index' – An index that ranks carbohydrates on a scale of 0-100 based on how fast these carbs are broken down and how soon blood-sugar levels rise in our body, 100 being the fastest. Carbs that have a rating of 55 or less are considered to be low GI. These break down relatively slowly and do not lead to a sudden spike in the insulin levels. 
Most snacks, sodas, food that contains high fructose corn syrup (Watch what you buy! – Will write about HFCS soon) white bread, white rice, burgers, essentially all refined carbs rank high on the index. These are also called high GI food. You may want eat as less of all this as you can. The more refined carbs you consume, the more likely you are to have a high blood-sugar and insulin levels. Higher your insulin levels throughout the day, more fat gain over time.
A list of various food items on the GI Index can be found here:http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm
The only two times of the day when your body can afford to consume simple carbs are
  1. After your wake up: Your body has been on a fast for the past 6 hours or so. Glycogen levels in your body are low and it has been breaking down your muscles for energy. A simple carb breakfast mixed with some complex carbs will bring back the glycogen levels to normal and signal your body to stop breaking down the muscles for fuel. Have a good amount of proteins help rebuild the muscles that were broken down.
2. Within 30 minutes of workout: You've used up glycogen during your workout and torn your muscles. Have high GI food with a good amount  of protein (40g) to restore glycogen and rebuild your muscles.
Avoiding abnormal insulin spikes and controlling blood-sugar levels doesn't only help in preventing fat gain, but will also help you prevent Type-II diabetes, heart diseases etc.

Should I tip in Japan?

So you're all set to either visit or live in Japan as an expat. You've brushed up on your casual Japanese to make sure you're the most polite guest you can be, you've read up on customs, you're familiar with

What did you do to change your life?

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Are one arm pull-ups and one finger pull-ups bad for your shoulders?

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