We cant really say anything for sure about how your body will react, but we can give you some advice.
As I understand this question, youre asking us about weight/looks, and NOT athletic performance, and your "training sessions" also dont indicate that youre working on improvement. You are just doing some physical activity for health.
The short answer
We cant really say anything for sure, there are just too many variables. You should simply strictly control your bodyweight, and if you start putting on some unnecessary lbs, try increasing your activity on slack weeks or cutting on kcal intake on those weeks.
We are not considering performance, breaking the stress adaptation pattern does not worry us. You wont ruin your progress or strength gains, since youre not training for improvement.
Since we are discussing simple weight gain lets check how much calories you burn while running. A very rough estimate would be that by skipping your running you burn about 400kcal less on a daily basis. In a weeks perspective this sums up to 2800 kcal less burned per week. The estimate I gave includes your resting energy expenditure, ignores completely your speed and weight, and is flawed in many, many other ways but just bear with me. Lets say that the ADDED energy expenditure would be half of the mentioned amount, giving us 200kcal a day and 1400kcal a week. Around 7000kcal excess is said to make you store around 1kg of fat. If this was the case, you could be putting on an additional 1kg every 5 weeks
But this isnt the whole story! Lower physical activity may decrease your hunger and the amounts of food you eat on slack days. To be honest, its a LOT easier to cut 200kcal from food than to burn it exercising. A single donut has around 250kcal! Thats why all weight loss programs MUST include changes in diet. Simply exercising isnt enough.
Also, we cant really say, how your metabolism will react to the change of activity level. There are hormonal responces both to physical activity and the types/amounts of food we eat, everything is connected, and the variables are not independant.
You could write a scientific paper on the topic, even several, but the bottom line is this: we cant accurately predict how your body will adapt to your lifestyle changes, and you should try careful observation