A pattern of facts that many of us will recognise once we are through our twenties;¹

• one’s trousers become tighter
• in the shower, one notices a bit more mass on the torso than there was previously

i.e. you have noticed you have more adipose tissue than before.

Don’t panic, we can come up with a plan. First let us remind ourselves:

• stress and lack of sleep reduces insulin sensitivity, increasing the propensity to store fat²
• the human body obeys the laws of physics: mass will reduce when more energy is consumed then supplied

Trying to chill out and sleep more is easier said than done. We do know though that physical exercise is likely to help with both, so we can just concentrate on the second of those points. There are two ways we can do this:

• reduce energy in — i.e. consume fewer calories
• increase energy out — i.e. exercise

Taking these in turn:

My answer to the first is to have a light supper where vegetables feature. If we consider simple dishes along these lines e.g. tricolor salad³, good quality ingredients will go a long way in terms of satisfaction.

On exercise, my suggestion would be to establish a baseline of aerobic exercise, in minutes per day, which corresponds to the current level.

People who know about these things seem to suggest that increasing volume of exercise by about 10% week-on-week is appropriate. Say we currently do 15 minutes of aerobic exercise per day and we wish to hit a target of 30. Using these values as examples, we then wish to find out how many weeks $w$ this will take:

$(30 \times 7) = (15 \times 7) \times 1.1^w \\ 2 = 1.1^w \\ \ln 2 = w \ln 1.1 \\ \ln 2 / \ln 1.1 = w \approx 7.3$

So if we increase the volume of exercise by 10% week-on-week, in 7-8 weeks we will reach our target.